JP2008024040A - Braking force control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force control device capable of alleviating a sense of incongruity of a driver due to unintended increase in braking force. <P>SOLUTION: Wheel cylinders 3FR to 3RR in two braking systems are connected to a master cylinder 2 via two shut-off valves 6-1, 6-2. With the shut-off valves 6-1, 6-2 closed, target deceleration G is calculated based on the master cylinder pressure and depressing stroke amount. When only one of the shut-off valves 6-1, 6-2 becomes open, limitation to reduce fluctuation of the master cylinder pressure is performed so as to limit rapid increase in the target deceleration G. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking force control device capable of controlling the working fluid pressure to the wheel cylinder of each wheel by brake-by-wire, separately from the working fluid pressure from a master cylinder.

As a conventional braking force control device, for example, there is a device described in Patent Document 1. In this device, the master cylinder is connected to the left front wheel cylinder and the right front wheel cylinder via separate switching means (electromagnetic on-off valves), respectively, and can be braked by the master cylinder pressure. .
In the control by brake-by-wire (hereinafter, simply referred to as BBW control), the two switching means are closed and the communication between the master cylinder and the wheel cylinder is shut off, and the wheel cylinder of each wheel is set with the pump as the drive source. The braking force by is controlled. The target deceleration of the BBW control by the pump is calculated based on both the brake pedal depression stroke amount and the master cylinder pressure.
JP 11-301434 A

  Here, in the BBW control in which a plurality of switching means are provided and the working fluid pressure of the wheel cylinder is increased by a pump which is a driving source different from the master cylinder, the brake pedal is depressed at the time of the BBW control. When braking is performed, only one switching means is switched from the shut-off state to the communication state due to a failure, some wheel cylinders communicate with the master cylinder, and the pressure of the remaining wheel cylinders is calculated as above. Assuming the situation where the target deceleration is controlled, the high-pressure wheel cylinder and the low-pressure master cylinder are in communication at the moment when some of the wheel cylinders and the master cylinder are switched from the shut-off state to the communication. The master cylinder pressure rises rapidly. Further, when the master cylinder pressure rises rapidly, a kickback phenomenon occurs in which the brake pedal is pushed back.

When such a failure occurs and the kickback phenomenon occurs, the master cylinder pressure suddenly rises even though the brake pedal is not depressed, resulting in an increase in the target deceleration calculated based on the master cylinder pressure. An increase in braking force unintended by the driver occurs, giving the driver a sense of incongruity.
The present invention has been made paying attention to the above points, and an object of the present invention is to provide a braking force control device that can alleviate a sense of incongruity due to an increase in braking force not intended by the driver.

In order to solve the above problems, the present invention provides a master cylinder that outputs a master cylinder pressure corresponding to a depression stroke of a driver's brake pedal, a plurality of wheel cylinders that communicate with the master cylinder, and a plurality of wheel cylinders. Dividing at least two into a plurality of braking systems, a plurality of switching means provided for each braking system for switching between communication and disconnection between the master cylinder and the wheel cylinder, and the master in a state of being shut off by the switching means Second braking control means for controlling the braking force of the wheel cylinder by a drive source different from the cylinder, wherein the second braking control means is at least the master cylinder pressure and the depression stroke amount of the brake pedal. The target deceleration is calculated based on the pressure, and the braking force of the wheel cylinder The braking force control apparatus for controlling such that,
From the state where two or more of the braking systems are shut off by the switching means and the brake pedal is depressed, only a part of the braking systems in the shut-off state has changed from shut-off to communication with the master cylinder. Is detected, the brake limiting means for limiting the fluctuation of the target deceleration is provided during the fluctuation of the master cylinder pressure due to the change from the shut-off state of the wheel cylinder and the master cylinder to the communication.

  According to the present invention, even if only some of the wheel cylinders communicate with the master cylinder during the BBW control, it is possible to suppress an unintended increase in braking force, and to reduce the uncomfortable feeling to the driver.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a braking force control apparatus according to the present embodiment.
(Constitution)
In FIG. 1, reference numeral 1 denotes a brake pedal 1 that constitutes a braking operator that is braked by a driver. The brake pedal 1 is connected to a hydraulic pressure booster and a master cylinder 2. The master cylinder 2 is connected to the respective wheel cylinders 3FR to 3RR through the first communication path 5-1 or the second communication path 5-2. In FIG. 1, reference numeral 4 denotes a reservoir.

In the present embodiment, the first communication passage 5-1 is connected to the wheel cylinder 3FR for the right front wheel and the wheel cylinder 3RL for the left rear wheel through the first electromagnetic cutoff valve 6-1. The second communication path 5-2 is connected to the wheel cylinder 3FL for the left front wheel and the wheel cylinder 3RR for the right rear wheel through the second electromagnetic cutoff valve 6-2.
Here, the electromagnetic shut-off valves 6-1 and 6-2 are in an open state when not energized, and the hydraulic pressure of the master cylinder 2 can be supplied to the wheel cylinders 3FR to 3RR. The electromagnetic shut-off valves 6-1 and 6-2 constitute switching means.

  In the present embodiment, the braking on the right front wheel side and the left rear wheel side communicating with the first communication path 5-1 constitutes the first braking system, and the left front wheel side communicating with the second communication path 5-2 and the right Rear wheel braking constitutes a second braking system, and BBW control is possible by individual pumps 8-1 and 8-2 as will be described later. Of course, the first brake system and the second brake system may be driven by the same pump.

The circuit configurations on the first braking system side and the second braking system side will be described. Since the circuit configuration of the first braking system and the circuit configuration of the second braking system are the same configuration, the configuration will be mainly described for the first braking system.
Reference numerals 7-1, 7-2 and 8-1, 8-2 denote braking force actuators (drive sources different from the master cylinder 4) for generating a braking force in the BBW control. 2 and hydraulic pumps 8-1 and 8-2 driven by the motors 7-1 and 7-2. The operations of the motors 7-1 and 7-2 are controlled by control signals (control currents) from the actuator controllers 9-1 and 9-2, and the hydraulic pump 8- 1 and 8-2 are driven. In FIG. 1, gear pumps are illustrated as the hydraulic pumps 8-1 and 8-2. The hydraulic pumps 8-1 and 8-2 have input ports connected to the reservoir 4 via second pipes 10-1 and 10-2, and discharge ports described above via third pipes 11-1 and 11-2. By being connected to the first communication path 5-1, the working fluid in the reservoir 4 is sucked through the second pipes 10-1 and 10-2, and the working fluid is sucked into the third pipes 11-1 and 11-. 2 can be discharged to the wheel cylinders 3FR to 3RR. In the middle of the third pipes 11-1 and 11-2, holding valves 12-1 and 12-2 made of electromagnetic proportional valves are inserted. The wheel cylinders 3FR to 3RR are connected to the second pipes 10-1 and 10-2 communicating with the reservoir 4 through the fourth pipes 13-1 and 13-2, and the fourth pipes 13-1 and 13-2 are connected. Connected to 13-2 are pressure reducing valves 14-1 and 14-2 comprising electromagnetic proportional valves. Reference numerals 15-1 and 15-2 denote relief valves, and reference numerals 16-1 and 16-2 denote check valves.
Here, each said valve is controlled by the command from corresponding actuator controller 9-1, 9-2.

  In the BBW control state, the shutoff valves 6-1 and 6-2 are closed, and when the pressure is increased, the holding valves 12-1 and 12-2 are opened, and the pressure reducing valves 14-1 and 14- 2 is closed, and the working fluid discharged from the pumps 8-1 and 8-2 is supplied to the wheel cylinders 3 FR to 3 RR to increase the pressure, and when the pressure is reduced, the holding valves 12-1 and 12-2 are closed. In this state, the pressure reducing valves 14-1 and 14-2 are opened, and the working fluid in the wheel cylinders 3FR to 3RR is returned to the reservoir 4 and depressurized. Note that the holding valves 12-1 and 12-2 are appropriately closed when the hydraulic pressure is held by slip control, front / rear braking force distribution control, or the like.

  Further, in FIG. 1, reference numeral 20 denotes a stroke simulator. The stroke simulator 20 is connected to the master cylinder 2 via an electromagnetic opening / closing valve 21. The electromagnetic on-off valve 21 is in a closed state when not energized, and is controlled in an open state in synchronization with the shutoff valves 6-1 and 6-2 being switched to a closed state by a command from the brake controller 22. As a result, the stroke simulator 20 operates. That is, during the BBW control, the master cylinder pressure Pmc is absorbed by the stroke simulator 20 to realize a natural pedal depression force.

The actuator controllers 9-1 and 9-2 are provided for each of the two braking systems, and the actuator controllers 9-1 and 9-2 correspond to the actuators of the corresponding braking system in response to a command from the brake controller 22. Control the state of
Here, reference numeral 24 denotes a stroke sensor, which detects the operation amount of the brake pedal 1 and outputs it to the brake controller 22. Reference numerals 23-1 and 23-2 are pressure sensors provided for each braking system for detecting the master cylinder pressure Pmc (corresponding to the driver's required braking amount). The detected pressure signal is sent to the brake controller 22. Output. The pressure signals detected by the two pressure sensors 23-1, 23-2 are substantially the same except in special cases. Reference numerals 25FR to 25RR are pressure sensors that detect the wheel cylinder pressure Pwc of each of the wheel cylinders 3FR to 3RR, and output the detected pressure signal to the brake controller 22. Reference numerals 26-1 and 26-2 are pressure sensors that detect the discharge pressures of the pumps 8-1 and 8-2, and output the detected pressure signals to the brake controller 22.

  The brake controller 22 is constituted by, for example, a CPU, ROM, RAM, digital port, A / D port, and a one-chip microcomputer incorporating various timer functions (or a plurality of chips realizing the same function). The brake controller 22 outputs control signals to the valves and the motors 7-1 and 7-2 via the actuator controllers 9-1 and 9-2.

During normal control, the brake controller 22 closes the electromagnetic shut-off valves 6-1 and 6-2 as the second braking control state so that the BBW control state is established, and opens the electromagnetic on-off valve 21 for the stroke simulator 20. The stroke simulator 20 is operated as a state to enable a natural pedal effort.
Further, when a failure is detected such that the hydraulic pressure cannot be generated by the pumps 8-1 and 8-2, the first electromagnetic cutoff valve 6-1 and the second electromagnetic cutoff valve 6-2 are set as the first braking control state. Is opened, and the electromagnetic on-off valve 21 for the stroke simulator 20 is returned to the closed state, and the hydraulic pressure of the master cylinder 2 is supplied to each wheel cylinder via the first communication path 5-1 and the second communication path 5-2. Introduced into 3FR-3RR.

Next, the control (BBW control) in the second braking control state in the brake controller 22 will be described. This process constitutes a second braking control means.
In addition, although it does not appear in the following process, when abnormality which may not be able to make all the brake control systems function normally is detected, it supplies with electricity to each valve and motor 7-1, 7-2. That is, the first electromagnetic cutoff valves 6-1 and 6-2 and the second electromagnetic cutoff valves 6-1 and 6-2 are both opened, and the on-off valve 21 for the stroke simulator 20 is closed. The hydraulic pressure of the master cylinder 2 is returned to the wheel cylinders 3FR to 3RR via the first communication path 5-1 and the second communication path 5-2, and the first braking control state is set.

  As shown in FIG. 2, the system operates at a predetermined sampling period. First, in step S10, it is determined whether or not a system failure has occurred. If it is determined that there is a failure, the process proceeds to step S20, which is not a failure. If it is determined, the process proceeds to step S130. The system failure is, for example, controller failure of one system, motors 7-1 and 7-2, pumps 8-1 and 8-2, or the like.

In step S20, it is determined whether or not the shut-off valves 6-1 and 6-2 of the brake control system on the failure side are in an open state. If it is determined to be in an open state, the process proceeds to step S30 and is determined to be in a closed state. In this case, the process proceeds to step S130.
In step S30, the master cylinder pressure Pmc0 immediately before the cutoff valves 6-1 and 6-2 are opened, and the cutoff valves 6-1 and 6-2 on the side where the cutoff valves 6-1 and 6-2 are opened. The differential pressure Pdiff from the wheel cylinder pressure Pwc0 immediately before opening is calculated by the following formula, and the process proceeds to step S40.
Pdiff = Pwc0−Pmc0

  Here, the master cylinder pressure Pmc0 and the wheel cylinder pressure Pwc0 immediately before the shut-off valves 6-1 and 6-2 are opened are, for example, when the shut-off valves 6-1 and 6-2 are closed, The latest values of the pressure Pmc and the wheel cylinder pressure Pwc may be always stored. In this embodiment, since two wheel cylinders 3FR to 3RR are connected to each braking system, one of the pressures of the two wheel cylinders 3FR to 3RR may be set as the wheel cylinder pressure Pwc0. The average value of the pressures of the wheel cylinders 3FR to 3RR may be the wheel cylinder pressure Pwc0.

The process of step S30 is performed only at the first transition from step S20.
In step S40, it is determined whether or not the differential pressure Pdiff is greater than a predetermined threshold C1, and if it is greater, the process proceeds to step S50, and if it is less than or equal to the threshold C1, the process proceeds to step S130. That is, when the differential pressure Pdiff between the master cylinder pressure Pmc0 and the wheel cylinder pressure Pwc0 immediately before the shut-off valves 6-1 and 6-2 are opened is small, the master cylinder pressure Pmc does not fluctuate or is below an allowable level. Since the change is small, the process proceeds to step S130 without performing the following target deceleration G limiting process. The threshold value C1 is set in advance from the viewpoint of whether or not the fluctuation of the master cylinder pressure Pmc occurs more than allowable by experiments and calculations. The threshold value C1 may be a constant or a variable that changes depending on the contribution of the master cylinder pressure Pmc to the target deceleration.

  The process of step S40 detects the occurrence of the kickback phenomenon. However, if the brake pedal 1 is depressed, the process may proceed to step S50 as the occurrence of the kickback phenomenon. In step S40, it is not directly detected whether or not the brake pedal 1 is depressed. However, if the differential pressure Pdiff is larger than the predetermined threshold C1, the wheel cylinder is at a high pressure. This represents a state where the brake pedal 1 is depressed more than a predetermined amount.

In step S50, a pressure increase gradient ΔP of the master cylinder pressure Pmc is obtained, and it is determined whether or not it is larger than a threshold value C2. If it is larger than the threshold value C2, the process proceeds to step S60, and if it is less than the threshold value C2, the process proceeds to step S80.
Here, the threshold value C2 is set to a value larger than the step-up gradient that can be generated when the driver depresses the brake pedal 1. By setting in this way, if the pressure increase gradient ΔP is larger than the threshold value C2, it can be determined that deceleration unintended by the driver has occurred.

Further, the increase gradient ΔP of the master cylinder pressure Pmc may be obtained from a difference from the previous value, or may be obtained from an average value for a plurality of times.
In step S60, a master pressure correction value Pcompen is calculated based on the following equation from the current master cylinder pressure Pmc and the master cylinder pressure Pmc0 immediately before the shutoff valves 6-1 and 6-2 are opened, and the process proceeds to step S70. .
Pcompen = Pmc−Pmc0
In step S70, as shown in the following equation, the value obtained by subtracting the master pressure correction value Pcompen from the current master cylinder pressure Pmc is set as the master cylinder pressure P for calculating the target deceleration degree Gp, and the process proceeds to step S140. .
P = Pmc-Pcompen
As a result, the master cylinder pressure P for calculating the target deceleration degree Gp is limited to be small.

  Here, in the present embodiment, as can be seen from the processing in step S60 and step S70, while the master cylinder pressure Pmc is rapidly increased by connecting some of the wheel cylinders 3FR to 3RR and the master cylinder 2, This is an example in which the master cylinder pressure P for calculating the target deceleration Gp is the master cylinder pressure Pmc0 immediately before the shut-off valves 6-1 and 6-2 are opened.

On the other hand, if it is determined in step S50 that the master cylinder pressure increasing pressure ΔP is equal to or less than the threshold value C2 and the process proceeds to step S80, that is, after determining that the pressure is rapidly increasing, the stroke variation ΔS of the brake pedal 1 is greater than or equal to zero. If it is determined whether the brake pedal 1 is held down or further depressed, the process proceeds to step S90, and it is determined that the brake pedal 1 is depressed. In step S100, the process proceeds to step S100.
Here, the stroke fluctuation amount ΔS takes a positive direction in which the stepping stroke amount increases. The stroke fluctuation amount ΔS may be a difference from the previous value, or may be obtained from an average value of a plurality of times.

In step S90, the master pressure correction amount Pcompen is subtracted by the decreasing gradient C3 by the following equation, and the process proceeds to step S120.
Pcompen = Pcompen -C3
However, when Pcompen ≦ 0, Pcompen = 0.
The decreasing gradient C3 is a positive value and is set to a deceleration fluctuation amount that does not give the driver a sense of incongruity.
On the other hand, in step S100, it is determined whether or not the brake pedal 1 has been returned and the current stroke amount S of the brake pedal 1 has become equal to or less than the loss stroke Sloss. If greater than the loss stroke Sloss, the process proceeds to step S120. If it is equal to or less than the loss stroke Sloss, the process proceeds to step S110.

  The loss stroke Sloss is the stroke amount at the boundary where the master cylinder pressure starts to rise when the stroke amount is depressed from zero. When the stroke amount is from zero to the loss stroke Sloss, it is a non-braking instruction position and the master cylinder 2 and the reservoir 4 are in a communication state. The kickback phenomenon occurs due to an unexpected backflow of the working fluid from the wheel cylinders 3FR to 3RR to the master cylinder 2. However, when the stroke amount is shorter than the loss stroke, the master cylinder 2 communicates with the reservoir 4. Therefore, since the working fluid that has flowed back to the master cylinder 2 escapes to the reservoir 4, the hydraulic pressure fluctuation does not occur or is small.

In step S110, the master pressure correction amount Pcompen is cleared to zero, that is, the restriction by the correction amount is removed, and the process proceeds to step S120.
In step S120, a value obtained by subtracting and limiting the master pressure correction value Pcompen from the current master cylinder pressure Pmc as the master cylinder pressure P for calculating the target deceleration degree Gp as shown in the following equation is determined in step S140. Migrate to
P = Pmc-Pcompen
Here, the master pressure correction value Pcompen is gradually set to a small value while the stroke of the brake pedal 1 is maintained or increased by the operation of the driver by the processing of the steps S80 to S110. Is returned, the master pressure correction value Pcompen is not changed.

In step S130, the current master cylinder pressure Pmc value is set as the master cylinder pressure P for calculating the target deceleration degree, and the process proceeds to step S140.
In step S140, the target deceleration G is calculated based on the master cylinder pressure P for calculation and the depression stroke amount S of the brake pedal 1, and the wheel cylinder pressure Pwc of each wheel that becomes the target deceleration G is calculated. The control command value that becomes the wheel cylinder pressure Pwc is output to each of the two actuator controllers 9-1 and 9-2, and then returned. For example, the control currents of the motors 7-1 and 7-2 are controlled based on the difference between the calculated target deceleration G and the current deceleration.

Here, calculation of the target deceleration G of the present embodiment will be described.
The target deceleration Gp due to the master cylinder pressure P is obtained by multiplying the master cylinder pressure P by a predetermined gain K2, for example, based on FIG.
Gp = K2 × Pm
Further, the target deceleration Gs is obtained from the stroke amount S based on a map as shown in FIG.
Then, the final target deceleration G is calculated from the target decelerations Gp and Gs of both the stroke amount S and the master cylinder pressure P based on the following equation.
G = (1-α) × Gs + α × Gp

Here, α is a weighting contribution coefficient that takes a value in the range of 0 to 1, and is determined by the previous target deceleration Gm−1 as shown in FIG. It sets so that the contribution of the target deceleration Gp based on the master cylinder pressure increases as −1 increases. Although the previous target deceleration Gm-1 is used in FIG. 5, the horizontal axis may be the master cylinder pressure. In this case, the master cylinder pressure P for the above calculation is preferable.
Here, Steps S10 to S70 constitute a braking restriction unit.

(Function and effect)
In the braking force control apparatus having the above configuration, in the normal control state (second braking control state), the target deceleration G is calculated based on the master cylinder pressure P and the depression stroke amount S, and the first braking system and the first braking system In each of the two braking systems, the wheel cylinders 3FR to 3RR are in a high pressure state when the pumps 8-1 and 8-2 are driven and the brake pedal 1 is depressed so that the target deceleration G is obtained. It has become.

  When the brake pedal 1 is depressed at the time of this BBW control, the first braking system side fails, for example, the actuator controller CPU on the first braking system side fails, and the first electromagnetic cutoff valve When 6-1 shifts from closed to open, the right front wheel wheel cylinder 3FR and the left rear wheel wheel cylinder 3RL communicate with the master cylinder 2. At this time, since the brake pedal 1 is generally depressed and the wheel cylinders 3FR and 3RL are higher in pressure than the master cylinder 2, the hydraulic pressure in the master cylinder 2 suddenly increases. Further, when the hydraulic pressure in the master cylinder 2 is suddenly increased, a kickback phenomenon occurs in which the brake pedal 1 is pushed back. Further, as described above, the target deceleration G of the second braking system is set so as to increase as the master cylinder pressure P and the stepping stroke amount S increase. Therefore, the master cylinder pressure Pmc that has suddenly increased. When the is used, the target deceleration G also rises rapidly, and braking exceeding the braking intended by the driver occurs, giving the driver a sense of incongruity.

  On the other hand, in the control of the present embodiment, when the first electromagnetic shut-off valve 6-1 is opened and the increase gradient of the master cylinder pressure is larger than C2, the master cylinder for calculating the target deceleration Gp. By limiting the pressure P to the value Pmc0 immediately before the first electromagnetic shut-off valve 6-1 is opened, the target deceleration G on the second braking system side rapidly increases even if the master cylinder pressure Pmc rapidly increases. It is possible to suppress the uncomfortable feeling to the driver at the time of the failure.

A time chart of this braking control is shown in FIG. A solid line indicates a case where the target deceleration G is not limited as described above, and a broken line portion indicates a case where the target deceleration G is limited during rapid pressure increase.
Here, even if the first electromagnetic shut-off valve 6-1 is opened from the closed state as described above, immediately before the first electromagnetic shut-off valve 6-1 is closed, for example, the depression stroke amount of the brake pedal 1 is small. When the differential pressure Pdiff between the master cylinder pressure Pmc0 and the wheel cylinder pressure Pwc0 is small, the increase in the master cylinder pressure Pmc when the first electromagnetic shut-off valve 6-1 is opened from the closed state is small. Limiting the increase of the target deceleration G is not performed (step S40).

  Further, when the master cylinder pressure Pmc is suddenly increased due to the failure, the master cylinder pressure P for calculating the target deceleration is corrected by being reduced by the master pressure correction value Pcompen, and then the wheel cylinders 3FR to 3RR are limited. When the brake pedal 1 is maintained or depressed by the driver after the rapid increase of the master cylinder pressure Pmc when the cylinder and the master cylinder 2 communicate with each other (the pressure increase gradient exceeds C2) is completed. Accordingly, it is necessary to increase the target deceleration accordingly. At this time, if the restriction is suddenly stopped, the target deceleration is suddenly changed to give the driver a sense of incongruity.

On the other hand, in this embodiment, when the variation of the depression stroke amount is zero or increasing, the limit is gradually decreased so as to gradually decrease the master pressure correction value Pcompen, thereby suppressing the sudden change in the target deceleration. However, the deceleration is increased in accordance with the driver's depression of the brake pedal 1.
On the other hand, when the brake pedal 1 is returned by the driver, by holding the master pressure correction value Pcompen, the deceleration is lowered according to the driver's brake pedal 1 to suppress the occurrence of uncomfortable feeling.

While the master cylinder pressure Pmc suddenly increases due to the above-mentioned failure, the master cylinder pressure P for calculation is set to a value Pmc0 immediately before the shut-off valve 6-1 is opened, but the master pressure correction value Pcompen is always Is processed so as to be a differential pressure between the current master cylinder pressure Pmc.
The master pressure correction value Pcompen is cleared to zero when the brake pedal 1 is returned to the loss stroke or less, and the master cylinder pressure P for calculation based on the master pressure correction value Pcompen is limited in the subsequent pedal stroke. There is no.

Here, although the case where the target deceleration G is calculated from both Gp based on the master cylinder pressure P and Gs based on the stepping stroke amount is illustrated in the above embodiment, the present invention is not limited to this. For example, this embodiment is applied even if the target deceleration G is Gp itself based on the master cylinder pressure P.
Further, in the above description, it is assumed that the target deceleration G increases as the master cylinder pressure increases, but even if the target deceleration G is set to decrease as the master cylinder pressure increases in some areas. The present embodiment is applicable. In this case, it is possible to prevent the target deceleration G from being reduced unintentionally due to a sudden increase in the master cylinder pressure Pmc.

Further, since the present invention is effective when the contribution of the master cylinder pressure to the target deceleration G is large, the target deceleration may be limited only when the contribution coefficient α is equal to or greater than a predetermined value.
In the above embodiment, when the wheel cylinders 3FR to 3RR are in communication with the master cylinder 2 and the master cylinder pressure Pmc is rapidly increasing, the master cylinder pressure immediately before the shut-off valves 6-1 and 6-2 are opened. Although the master cylinder pressure P for calculation is limited to Pmc0, the limitation is not limited to this. For example, the master cylinder pressure P for calculation may be limited by multiplying the master cylinder pressure Pmc by a correction coefficient β smaller than 1 as in the following equation.
P = β × Pmc
In this case, the correction coefficient β may be gradually increased toward 1 in step S90.

In the above embodiment, the case where the target deceleration G is limited by limiting the master cylinder pressure P for calculation is illustrated, but based on the target deceleration G or the master cylinder pressure calculated in step S140. The target deceleration Gp may be directly limited.
Moreover, although the case where there are two braking systems is illustrated in the above embodiment, the wheel cylinders may be divided into three or more and the braking systems may be classified into three or more systems.

  Moreover, in the said embodiment, although all four wheels are divided into two braking systems, it is not limited to this. For example, the wheel cylinder communicating with the first communication path 5-1 may be only the wheel cylinder 3FR for the right front wheel, and the wheel cylinder communicating with the second communication path 5-2 may be only the wheel cylinder 3FL for the left front wheel. That is, in the second braking control state (BBW control), the four wheels can be braked, and in the second braking state in which the shut-off valves 6-1 and 6-2 are opened, only the front wheels are in a brakeable state. There may be.

It is a schematic diagram which shows the circuit structure based on Embodiment based on this invention. It is a figure explaining the process of the brake controller which concerns on embodiment based on this invention. It is a figure which shows the relationship between a master cylinder pressure and the target deceleration Gp. It is a figure which shows the relationship between the depression stroke amount and the target deceleration Gs. It is a figure which shows the relationship of the contribution coefficient (alpha). It is a figure which shows the example of a time chart which concerns on embodiment based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 3FR-3RR Wheel cylinder 5-1 1st communication path 5-2 2nd communication path 6-1 and 6-2 Electromagnetic cutoff valve (switching means)
7-1, 7-2 Motor (another drive source)
8-1, 8-2 Pump (another drive source)
9-1, 9-2 Actuator controller 22 Brake controller S Stroke amount Pmc Current master cylinder pressure Pmc0 Master cylinder pressure P just before the shut-off valve is opened Master cylinder pressure Pcompen Master pressure correction value Pwc Wheel cylinder pressure Pwc0 Wheel cylinder pressure α immediately before the shut-off valve is opened Contribution coefficient G Target deceleration Gp Target deceleration Gs based on master cylinder pressure Target deceleration based on stroke amount

Claims (8)

A master cylinder that outputs a master cylinder pressure corresponding to the depression stroke of the brake pedal of the driver, and a plurality of wheel cylinders that communicate with the master cylinder;
A plurality of switching means for classifying at least two of the plurality of wheel cylinders into a plurality of braking systems, and switching between communication and blocking between the master cylinder and the wheel cylinders provided for each braking system;
Second braking control means for controlling the braking force of the wheel cylinder by a driving source different from the master cylinder in a state of being shut off by the switching means, and the second braking control means is configured to control the master cylinder pressure and the brake pedal. In the braking force control device that calculates the target deceleration based on at least the master cylinder pressure of the stepping stroke amount and controls the braking force of the wheel cylinder to be the target deceleration,
From the state where two or more of the braking systems are shut off by the switching means and the brake pedal is depressed, only a part of the braking systems in the shut-off state has changed from shut-off to communication with the master cylinder. A braking force limiting device for limiting the fluctuation of the target deceleration during fluctuations in the master cylinder pressure due to a change from the shut-off state of the wheel cylinder and the master cylinder to communication.   The change in the master cylinder pressure due to the change from the shut-off state of the wheel cylinder and the master cylinder to the communication is larger than the change that can be generated by the operation of the brake pedal by the driver. Braking force control device.   The braking limiting means limits the fluctuation of the target deceleration by setting the master cylinder pressure just before the partial braking system is changed from shut-off to communication as the master cylinder pressure when calculating the target deceleration. The braking force control apparatus according to claim 1 or 2, characterized in that   The braking force control device according to any one of claims 1 to 3, wherein each braking system has a drive source different from the master cylinder.   The limit is gradually reduced when it is determined that the amount of stepping stroke is being held or increased after the stepping stroke is returned to the non-braking command position after the restriction by the braking restriction means is activated. The braking force control apparatus according to any one of claims 1 to 4.   6. The control device according to any one of claims 1 to 5, wherein the limitation is maintained while the stepping stroke amount is decreasing before the stepping stroke is returned to the non-braking instruction position after the limitation by the braking limiting unit is activated. A braking force control apparatus according to claim 1.   The braking force control device according to any one of claims 1 to 6, wherein the restriction is stopped when the master cylinder communicates with a reservoir. A master cylinder that outputs a master cylinder pressure corresponding to the depression stroke of the brake pedal of the driver, and a plurality of wheel cylinders that communicate with the master cylinder;
A plurality of switching means for classifying at least two of the plurality of wheel cylinders into a plurality of braking systems, and switching between communication and blocking between the master cylinder and the wheel cylinders provided for each braking system;
Second braking control means for controlling the braking force of the wheel cylinder by a driving source different from the master cylinder in a state of being shut off by the switching means, and the second braking control means is configured to control the master cylinder pressure and the brake pedal. In the braking force control device that calculates the target deceleration based on at least the master cylinder pressure of the stepping stroke amount and controls the braking force of the wheel cylinder to be the target deceleration,
From the state where two or more of the braking systems are shut off by the switching means and the brake pedal is depressed, only a part of the braking systems in the shut-off state has changed from shut-off to communication with the master cylinder. When the amount of change in the increase in the master cylinder pressure is equal to or greater than a predetermined value, a braking force control device is provided that includes a braking restriction unit that restricts an increase in the target deceleration.

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