JP4888075B2 - Braking force control device - Google Patents

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, each wheel cylinder is connected to the master cylinder via an electromagnetic on-off valve, and braking is possible by the master cylinder pressure.
Also, during normal braking, during brake-by-wire control (hereinafter simply referred to as BBW control), the electromagnetic on-off valve is closed and communication between the master cylinder and the wheel cylinder is shut off, and the pump is operated as a drive source. The braking force by the wheel cylinder of each wheel is controlled.

  The target deceleration G of the BBW control by the pump is calculated based on both the brake pedal depression stroke amount and the master cylinder pressure. That is, the first temporary target deceleration Gp is calculated based on the master cylinder pressure, and the second temporary target deceleration Gs is calculated based on the stepping stroke amount. The following formulas are used for the two temporary target decelerations Gp and Gs. As described above, the final target deceleration G is calculated by weighting the contribution α.

G = α · Gp + (1-α) Gs
The contribution α is set so that the contribution degree of the master cylinder pressure increases as the previous target deceleration (substantially synonymous with the master cylinder pressure) increases, and the master cylinder pressure exceeds a predetermined level when the brake pedal is depressed. In this state, the master cylinder pressure is emphasized, and for example, the contribution degree of the master cylinder pressure is 100%.

The contribution α is set for the following reason. That is, since there is a delay in the generation of the master cylinder pressure at the start of the depression of the brake pedal, the contribution degree of the depression stroke amount is set to be large (contribution α is small) when the depression stroke amount is small. In addition, in relation to the depression force and stroke amount of the brake pedal, the greater the depression stroke amount, the smaller the increase in stroke amount with respect to the increase in depression force. Therefore, when the depression stroke amount is large, the contribution degree of the master cylinder pressure is increased ( The contribution degree α is set large). As a result, the depression force of the brake pedal operated by the driver can be accurately reflected in braking.
JP 11-301434 A

  As described above, when the brake pedal depression amount is small and the master cylinder pressure is small, the degree of contribution to the target deceleration is such that the stepping stroke amount, that is, the stroke amount with a large contribution degree of the second temporary target deceleration Gs is emphasized. In addition, when the brake pedal is depressed and the master cylinder pressure is larger than a predetermined level, the master cylinder pressure, that is, the contribution degree of the first temporary target deceleration Gp is emphasized. Between the emphasis on the stroke amount and the emphasis on master cylinder pressure, there is a transition period from emphasis on stroke amount to emphasis on master cylinder pressure (a state in which the rate of change of the contribution is large), and the master cylinder pressure is reduced when the brake pedal is depressed. The master cylinder pressure and the contribution degree α so that the transition from the state in which the contribution degree of the second temporary target deceleration Gs is large to the state in which the contribution degree of the first temporary target deceleration Gp is large goes smoothly as it increases. Is set.

  Such a setting of the contribution degree α is set based on the time when the brake pedal is depressed and braking is increased. However, in general, due to the hysteresis of the master cylinder and brake pedal, the relationship between the master cylinder pressure and the pedal stroke differs between when the brake pedal is depressed and when it is returned, and when the pedal is returned, the speed of the pedal stroke decreases. On the other hand, the decreasing speed of the master cylinder pressure tends to increase.

For this reason, the target deceleration G is temporarily increased in spite of the brake pedal being returned in the transition period in which the master cylinder pressure emphasis state shifts to the stroke amount emphasis state during the pedal returning operation. When the brake pedal is returned, the operation direction of the brake pedal may not match the change direction of the target deceleration. Such a phenomenon gives an uncomfortable feeling to the driver.
The present invention has been made paying attention to the above points, and it is an object of the present invention to provide a braking force control device capable of reducing the uncomfortable feeling at the time of brake return operation in a brake-by-wire.

In order to solve the above problems, the present invention provides a master cylinder that outputs a master cylinder pressure corresponding to a driver's brake pedal depression stroke, and a target deceleration based on the master cylinder pressure and the brake pedal depression stroke amount. Braking control means for controlling the braking force of the wheel cylinder to calculate and achieve the target deceleration, the degree of contribution of the master cylinder pressure when calculating the target deceleration increases as the master cylinder pressure increases In the braking force control apparatus set as described above, the braking force control device further includes a rising limit unit that limits a temporary increase in the target deceleration caused by a change in the degree of contribution during the return of the brake pedal. When the target deceleration is estimated to or rises up during, to limit the increase of the target deceleration It is an butterfly.

  According to the present invention, in the BBW control, it is possible to suppress or reduce the temporary increase of the target deceleration that may occur when the brake pedal is returned, and as a result, to the driver when the brake pedal is returned. Giving a sense of incongruity can be reduced or suppressed.

Next, a first embodiment 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 3RR for the left rear wheel through the first electromagnetic shut-off valve 6-1. The second communication passage 5-2 is connected to the wheel cylinder 3FL for the left front wheel and the wheel cylinder 3RL 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 drawn into the third pipe 11-1, It is possible to discharge to the wheel cylinders 3FR to 3RR via 11-2. 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 to be 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 P is absorbed by the stroke simulator 20 to realize a natural pedal effort.

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 that are provided for each braking system and detect a master cylinder pressure P (corresponding to a driver's required braking amount), and send the detected pressure signal 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 with reference to FIG. This process constitutes a braking control means.
If an abnormality that does not appear in the following process but may cause the braking control system to not function normally is detected, the power supply to each valve and the motors 7-1 and 7-2 is cut off. 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 returned to the closed state. Then, the hydraulic pressure of the master cylinder 2 is introduced into each of the wheel cylinders 3FR to 3RR through 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, it operates at every predetermined sampling period. First, in step S10, various information is input and the process proceeds to step S20.
In step S20, the pedal depression force Fs based on the depression stroke amount S is calculated based on the map as shown in FIG. 3, and the process proceeds to step S30. The stepping stroke amount S is set to a value along the map as shown in FIG. 3 in view of the fact that the larger the amount of increase in the stepping force with respect to the stroke change, the larger the stepping stroke amount S.

In step S30, the pedal depression force Fp based on the master cylinder pressure P is calculated based on the map as shown in FIG. 4, and the process proceeds to step S40. Since the master cylinder pressure P has a substantially linear relationship with the pedal effort, the master cylinder pressure P is set to be a map as shown in FIG.
In step S40, based on the map as shown in FIG. 5 using the current master cylinder pressure P, a contribution degree α that takes a larger value as the master cylinder pressure P increases is determined, and the process proceeds to step S50.

  That is, in the region where the master cylinder pressure P is small due to the small depression stroke amount S at the depression start timing of the brake pedal 1, the contribution degree α is made small and the depression stroke amount is emphasized, and the depression stroke amount S is large and the predetermined master When the cylinder pressure is equal to or higher than the cylinder pressure P, the contribution degree α is increased so that the master cylinder pressure P is emphasized, and in the high G region, the contribution degree α is set to 1 (= 100%). This contribution degree α is a value from 0 to 1, indicating the contribution degree on the master cylinder pressure P side, and the contribution degree on the stepping stroke side is (1−α).

In step S50, using the depression force Fs and Fp based on the depression stroke amount S and the master cylinder pressure P, a combined depression force Fps for calculating the target deceleration G is calculated based on the following equation, and the process proceeds to step S60. .
Fps = α × Fp + (1−α) × Fs
In step S60, it is determined whether or not the brake pedal 1 is being returned. If it is determined that the brake pedal 1 is being returned, the process proceeds to step S70, and if it is determined that the brake pedal 1 is being held or depressed, the process proceeds to step S100. The above determination may be made based on the change in the stepping stroke amount S. The change may be a comparison with the previous value, or may be a comparison with an average value for a plurality of past times (for example, 6 times) in consideration of fluctuations.

In step S70, the current combined pedal force Fps and the lowest value Fpsmin are compared. If the lowest value Fpsmin is larger, the combined pedal force Fps is substituted for the lowest value Fpsmin, and the process proceeds to step S80. Note that the lowest value Fpsmin is set to a large value as an initial value at the time of depression, for example.
In step S80, it is determined whether or not the composite pedaling force Fps is increasing. If it is determined that the combined pedal effort Fps is increasing, the process proceeds to step S90. If it is determined that it is not increasing, the process proceeds to step S100.
In step S90, as shown in the following equation, the lowest value Fpsmin is substituted for the combined pedaling force Fps to limit the increase in the combined pedaling force Fps, and the process proceeds to step S100.
Fps = Fpsmin
In step S100, based on the map as shown in FIG. 6, the target deceleration G corresponding to the composite pedaling force Fps is calculated, and the process proceeds to step S110.

  In step S110, the wheel cylinder pressure Pwc of each wheel that becomes the target deceleration G is calculated, and the control command value that becomes the wheel cylinder pressure Pwc is output to the actuator controllers 9-1 and 9-2, and then returned. . For example, the control current of the motors 7-1 and 7-2 is controlled based on the difference between the calculated target deceleration G and the current deceleration. Each wheel cylinder pressure Pwc is determined in consideration of vehicle weight, brake rotor effective diameter, tire moving radius, brake pad μ, road surface μ, vehicle posture, and the like.

Here, in the above description, the pedal depression forces Fs and Fp based on the depression stroke amount and the master cylinder pressure P are calculated once in steps S20 and S30, and the pedal depression forces Fs and Fp are obtained from the master cylinder pressure P. Although the process of calculating the combined pedaling force Fps by weighting with the contribution degree α and converting the combined pedaling force Fps into the target deceleration G has been described, the present invention is not limited to this. In steps S20 and S30, each target deceleration based on the stepping stroke amount S and the master cylinder pressure P is calculated, and each target deceleration is finally weighted by the contribution α obtained from the master cylinder pressure P. A target deceleration G may be obtained. That is, the calculated pedaling forces Fs, Fp, and Fps are synonymous with the target deceleration and the final target deceleration based on the depression stroke amount and the master cylinder pressure P, respectively.
Here, steps S60 to S90 constitute a rise limiting means.

(Function and effect)
In the brake control device having the above-described configuration, when the brake pedal 1 is depressed, the target deceleration G is obtained with an emphasis on the depression stroke amount S at the initial depression, and the master cylinder pressure P is greater than a predetermined value when the master cylinder pressure P is greater than a predetermined value. By changing the degree of contribution α so as to place importance on P, it is possible to accurately reflect the driver's braking force on the deceleration. Note that the pedal feeling is secured by the stroke simulator in a state close to the state in which the master cylinder and the wheel cylinder communicate with each other.
The relationship between the master cylinder pressure P and the contribution degree α is set on the basis of a change when the brake pedal 1 is depressed, so that when the brake pedal 1 is depressed, the depression stroke amount S is emphasized. In the transition period in which the emphasis is placed on the master cylinder pressure P, the target deceleration G changes smoothly.

  On the other hand, when the pedal is returned by the driver's operation from the state where the brake pedal 1 is depressed and high braking is generated until the contribution degree α of the master cylinder pressure P becomes large, the contribution degree α is Considering the transition period (state in which the change in contribution is fast) from the state 1 to 0, the change rate of the master cylinder pressure P is greater when returning than when it is depressed due to hysteresis and the like. When the contribution α is small and the shift from emphasizing the master cylinder pressure P to emphasizing the stroke amount, the depression force Fp obtained from the master cylinder pressure P is obtained from the depression stroke amount S compared to when the pedal is depressed. It becomes smaller than the pedaling force Fs. For this reason, as shown in FIG. 7, although the brake pedal 1 is returned, the combined pedaling force Fps, that is, the target deceleration G, may temporarily increase to give the driver a feeling of strangeness.

On the other hand, in the present embodiment, when it is determined that the combined pedal force increases at the time of return, the composite pedal force Fps is increased as shown in FIG. 8 by limiting the composite pedal force Fps to the lowest value Fpsmin at the time of return. However, the increase of the target deceleration G is suppressed.
FIG. 9 shows an example of a time chart at that time. As shown in this time chart example, during braking return, the combined pedal force, that is, the value of the target deceleration G, is limited to the lower value Fpsmin that is sequentially updated, thereby suppressing the temporary increase of the target deceleration G. It is done.
In this manner, even when the pedaling force Fs and Fp (synonymous with the target deceleration G) calculated based on the depression stroke amount S and the master cylinder pressure P are misaligned during pedal return, the combined pedaling force Fps, that is, The occurrence of a temporary increase in the target deceleration G can be limited. As a result, it is possible to eliminate the uncomfortable feeling when the pedal is returned.

  In particular, in the present embodiment, when the resultant pedal effort Fps is to be increased, the increase in the target deceleration G can be reliably suppressed by limiting to the lowest value Fpsmin during pedal return. That is, the deviation of each depression force (synonymous with the target deceleration G) calculated based on the depression stroke amount S and the master cylinder pressure P tends to increase as the return speed of the brake pedal 1 increases. Regardless of the above, by limiting the increase to the lowest value Fpsmin, the increase of the target deceleration G can be surely suppressed.

Here, in the above embodiment, while the brake pedal 1 is being returned, the increase in the target deceleration G is always limited. However, it is performed only when the contribution α is smaller than 1. Also good. This is because the temporary increase in the target deceleration G occurs in the transition period when the contribution α is less than 1.
Here, if it is estimated that the target deceleration G rises or rises while the pedal is being returned (while the stepping stroke amount S is decreasing), the target deceleration G is limited to the lowest value Fpsmin as an increase limiting means for limiting the increase of the target deceleration G. Although the case is illustrated, it is not limited to this. For example, in the above embodiment, when it is determined that the target deceleration G increases even while the pedal is returned, the value of the contribution α at that time is decreased to limit the temporary increase of the target deceleration G. You may do it.

  Alternatively, when it is determined that the target deceleration G is increased despite the pedal being returned, the previous contribution α (before the target deceleration G is increased) until the brake pedal 1 is depressed again or the stroke becomes zero. The contribution α may be fixed, and the shift to emphasis on stroke may be stopped to limit the temporary increase in the target deceleration G. At this time, instead of the previous value, for example, by fixing the contribution degree α to 0.5 or the like, the transition to emphasis on stroke may be stopped to limit the temporary increase in the target deceleration G. . By fixing the contribution degree α in the middle of the transition period, an increase in the target deceleration G accompanying a change in the contribution degree during the return of the brake pedal 1 can be suppressed.

FIG. 10 shows a schematic diagram at that time, and FIG. 11 shows an example of the time chart. It can be seen that by fixing the contribution degree α before or at the beginning of the increase of the target deceleration G, the target deceleration G can be limited or not increased.
Moreover, although the case where there are two braking systems is illustrated in the above embodiment, the number may be one, or 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 the brake-by-wire using the fluid pressure is performed, it is not limited to this. Since it is only necessary to be able to control the braking force for the brake-by-wire, an electric brake that clamps the disc rotor with the brake pad or presses the brake shoe against the inner peripheral surface of the brake drum by controlling the driving of the electric actuator. Any brake may be used as long as it has an electronically controllable energy source such as a regenerative motor brake.

(Second Embodiment)
Next, a second embodiment will be described with reference to the drawings. In addition, about the apparatus similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
The basic configuration of this embodiment is the same as that of the first embodiment, but the second brake control state control (BBW control) in the brake controller 22 is different.
The process will be described with reference to FIG. This process constitutes a braking control means.
The system operates every predetermined sampling period. First, in step S200, various information is input and the process proceeds to step S210.

In step S210, it is determined whether or not the brake pedal is being returned. If it is determined that the brake pedal is being returned, the process proceeds to step S220, and if it is determined that the brake pedal is being held or depressed, the process proceeds to step S230. The above determination may be made based on the change in the stepping stroke amount S.
In step S220, the input master cylinder pressure P is filtered to limit the decrease rate. For example, a first-order lag function may be used as the filter.

Here, it is preferable to change the filter strength according to the change speed of the stepping stroke amount S. Specifically, as the change rate of the stepping stroke amount S is larger, the filter strength is increased to limit the decrease rate.
Similarly, it is preferable to change the filter strength according to the magnitude of deviation from the reference of the stepping stroke amount S. Specifically, the greater the deviation from the reference of the stepping stroke amount S, the higher the filter strength and the lowering speed is limited.

  Here, the above-mentioned reference means the depression stroke amount S and the master cylinder pressure P when the brake pedal is depressed at an average depression speed assumed to be most used in the normal running state as shown in FIG. The stepping stroke amount corresponding to the current master cylinder pressure P becomes the reference stroke amount S0. Based on the above relationship, a relationship of contribution α as shown in FIG. 5 is obtained. The deviation from the reference is positive when it is larger than the reference stroke amount acquisition S0.

In step S230, the pedal depression force Fs based on the depression stroke amount S is calculated based on the map as shown in FIG. 3, and the process proceeds to step S240. The stepping stroke amount S is set to a value along the map as shown in FIG. 3 in view of the fact that the larger the amount of increase in the stepping force with respect to the stroke change, the larger the stepping stroke amount S.
In step S240, the pedal depression force Fp based on the master cylinder pressure P is calculated based on the map as shown in FIG. 4, and the process proceeds to step S250. Since the master cylinder pressure P has a substantially linear relationship with the pedal effort, the master cylinder pressure P is set to be a map as shown in FIG.
In step S250, based on the map as shown in FIG. 5 using the current master cylinder pressure P, a contribution degree α that takes a larger value as the master cylinder pressure P increases is determined, and the process proceeds to step S260.

  That is, in a region where the depression stroke amount S is small and the master cylinder pressure P is small at the depression start timing of the brake pedal 1, the contribution α is made small and the depression stroke amount S is emphasized, and the depression stroke amount S is large and a predetermined master is set. When the cylinder pressure is equal to or higher than the cylinder pressure P, the contribution degree α is increased so that the master cylinder pressure P is emphasized, and in the high G region, the contribution degree α is set to 1 (= 100%). This contribution degree α is a value from 0 to 1, and indicates the contribution degree α on the master cylinder pressure P side, and the contribution degree α on the stepping stroke side is (1−α).

In step S260, using the depression force Fs and Fp based on the depression stroke amount S and the master cylinder pressure P, a combined depression force Fps for calculating the target deceleration G is calculated based on the following equation, and the process proceeds to step S270. .
Fps = α × Fp + (1−α) × Fs
In step S270, based on the map as shown in FIG. 6, the target deceleration G corresponding to the composite pedaling force Fps is calculated, and the process proceeds to step S280.

In step S280, the wheel cylinder pressure Pwc of each wheel that becomes the target deceleration G is calculated, and the control command value that becomes the wheel cylinder pressure Pwc is output to the actuator controllers 9-1 and 9-2, and then returned. . For example, the control current of the motors 7-1 and 7-2 is controlled based on the difference between the calculated target deceleration G and the current deceleration. Each wheel cylinder pressure Pwc is determined in consideration of vehicle weight, brake rotor effective diameter, tire moving radius, brake pad μ, road surface μ, vehicle posture, and the like.
Here, steps S210 and S220 constitute a rise restricting means.

(Function and effect)
As described above, because of the hysteresis and the like, the master cylinder pressure P changes more rapidly when the pedal is returned than when the pedal is depressed. When shifting from emphasis to stroke amount emphasis, the pedal effort determined from the master cylinder pressure P becomes smaller than the pedal effort determined from the depression stroke amount S, so that the pedal effort and depression stroke determined from the master cylinder pressure P are reduced. Deviation may occur in the pedal effort determined from the amount S, and the resultant pedal effort, that is, the target deceleration G, may temporarily increase to give the driver a sense of discomfort (see FIG. 7).

  On the other hand, in the present embodiment, when the pedal is returned, as shown in FIG. 14, by limiting the rate of decrease of the master cylinder pressure P to approach the rate of change of the master cylinder pressure P when the pedal is depressed, When the shift from the emphasis on the pressure P to the emphasis on the depression stroke amount S is shifted, the deviation of the depression force obtained from the depression force S calculated from the master cylinder pressure P and the depression stroke amount S is reduced, so that the combined depression force at the time of return, that is, the target reduction is reduced. It is possible to suppress a temporary increase in the speed G.

  Here, the higher the return speed of the brake pedal 1, the greater the deviation. In this embodiment, the higher the return speed of the brake pedal 1, the greater the restriction on the return speed of the master cylinder pressure P at the time of return. Thus, an increase in deviation can be prevented. As a result, it is possible to calculate an appropriate target deceleration G according to the driver's brake operation at any stepping speed.

  Further, with respect to the relationship between the master cylinder pressure P and the stepping stroke amount S used when setting the relationship between the master cylinder pressure P and the contribution degree α, the larger the current stepping stroke amount S, that is, the current stepping stroke amount S is. As the current stroke amount S is greater than the reference stroke amount S corresponding to the master cylinder pressure P, the pedaling force Fs (synonymous with the target deceleration G) determined by the step stroke amount S in the transition period. The deviation from the pedaling force Fp target deceleration G obtained by the master cylinder pressure P) becomes large. On the other hand, in the present embodiment, in this embodiment, the larger the deviation from the reference of the stepping stroke amount S, the larger the deviation of the master cylinder pressure P at the time of the return, thereby increasing the deviation. Can be prevented. As a result, it is possible to calculate an appropriate target deceleration G according to the driver's brake operation at any stepping speed.

FIG. 15 shows a time chart example. As shown in this time chart example, by restricting the decrease rate of the master cylinder pressure P when the pedal is returned and slowing the decrease rate closer to the change rate at the time of depression, the depression force Fp and depression based on the master cylinder pressure The changing speed of the pedaling force Fs based on the stroke amount S approaches when the pedal is depressed, and a temporary increase in the target deceleration G can be suppressed.
Other configurations and operational effects are the same as in the above embodiment.

(Third embodiment)
Next, a third embodiment will be described with reference to the drawings. In addition, about the apparatus similar to the said embodiment, the same code | symbol is attached | subjected and demonstrated.
The basic configuration of the present embodiment is the same as that of the first and second embodiments, but the second brake control state control (BBW control) in the brake controller 22 is different.
The process will be described with reference to FIG. This process constitutes a braking control means.
The system operates every predetermined sampling period. First, in step S400, various information is input, and the process proceeds to step S410.

In step S410, the pedal depression force Fs based on the depression stroke amount S is calculated based on the map as shown in FIG. 3, and the process proceeds to step S420. The stepping stroke amount S is set to a value along the map as shown in FIG. 3 in view of the fact that the larger the amount of increase in the stepping force with respect to the stroke change, the larger the stepping stroke amount S.
In step S420, the pedal depression force Fp based on the master cylinder pressure P is calculated based on the map as shown in FIG. 4, and the process proceeds to step S430. Since the master cylinder pressure P has a substantially linear relationship with the pedal effort, the master cylinder pressure P is set to be a map as shown in FIG.

In step S430, it is determined whether or not the brake pedal 1 is being returned. If it is determined that the brake pedal 1 is being returned, the process proceeds to step S440. If it is determined that the brake pedal 1 is being held or depressed, the process proceeds to step S450. The above determination may be made based on the change in the stepping stroke amount S.
In step S440, based on the map as shown in FIG. 5 using the current master cylinder pressure P, a contribution degree α that takes a larger value as the master cylinder pressure P increases is determined, and the process proceeds to step S460.

  That is, in a region where the depression stroke amount S is small and the master cylinder pressure P is small at the depression start timing of the brake pedal 1, the contribution α is made small and the depression stroke amount S is emphasized, and the depression stroke amount S is large and a predetermined master is set. When the cylinder pressure is equal to or higher than the cylinder pressure P, the contribution degree α is increased so that the master cylinder pressure P is emphasized, and the master cylinder pressure P0 becomes equal to or higher than a predetermined value. . This contribution degree α is a value from 0 to 1, and indicates the contribution degree α on the master cylinder pressure P side, and the contribution degree α on the stepping stroke side is (1−α). The master cylinder pressure P and the contribution degree α are set by obtaining the relationship between the stepping stroke amount S and the master cylinder pressure P at a predetermined stepping speed at the time of stepping (the stepping speed that is normally assumed to be the most used). Based on the relationship, the transition from the contribution amount α emphasizing the stroke amount to the contribution α emphasizing the master cylinder pressure P is set as smoothly as possible (the first and second described above). The same applies to the embodiment).

In step S450, the contribution degree α obtained from FIG. 5 is filtered to limit the rate of decrease of the contribution degree α, and the process proceeds to step S460. For example, a first-order lag function may be used as the filter.
Here, it is preferable to change the filter strength according to the change speed of the stepping stroke amount S. Specifically, as the change rate of the stepping stroke amount S is larger, the filter strength is increased to limit the decrease rate.

Similarly, it is preferable to change the filter strength according to the magnitude of deviation from the reference of the stepping stroke amount S. Specifically, the greater the deviation from the reference of the stepping stroke amount S, the higher the filter strength and the lowering speed is limited.
Here, the above-mentioned reference is a relationship between the depression stroke amount S and the master cylinder pressure P when the brake pedal 1 is depressed at the depression speed assumed to be most used in the normal running state as shown in FIG. Using the relationship, the stepping stroke amount S corresponding to the current master cylinder pressure P becomes the reference stroke amount. Based on the above relationship, a relationship of contribution α as shown in FIG. 5 is obtained. The deviation from the reference is positive when it is larger than the reference stroke amount.

In the above embodiment, the reduction rate is delayed by filtering the contribution degree α itself. However, a map having a slower reduction rate than that in FIG. 5 is prepared separately. Then, the final contribution degree α may be determined using the other map.
In step S460, using each stepping force Fs and Fp based on the stepping stroke amount S and the master cylinder pressure P, a combined pedaling force Fps for calculating the target deceleration G is calculated based on the following equation, and the process proceeds to step S470. To do.
Fps = α × Fp + (1−α) × Fs

In step S470, based on the map as shown in FIG. 6, the target deceleration G corresponding to the combined pedal force Fps is calculated, and the process proceeds to step S480.
In step S480, the wheel cylinder pressure Pwc of each wheel that becomes the target deceleration G is calculated, and the control command value that becomes the wheel cylinder pressure Pwc is output to each actuator controller 9-1 and 9-2, and then returned. . For example, the control current of the motors 7-1 and 7-2 is controlled based on the difference between the calculated target deceleration G and the current deceleration. Each wheel cylinder pressure Pwc is determined in consideration of vehicle weight, brake rotor effective diameter, tire moving radius, brake pad μ, road surface μ, vehicle posture, and the like.
Here, step S430 and step S450 constitute the rise limiting means.

(Function and effect)
As described above, because of the hysteresis and the like, the master cylinder pressure P changes more rapidly when the pedal is returned than when the pedal is depressed. When shifting from emphasis to stroke amount emphasis, the pedaling force determined from the master cylinder pressure P becomes smaller than the pedaling force determined from the stepping stroke amount S so that the master cylinder pressure is changed during the transition period of the contribution α. A deviation may occur between the pedaling force Fp obtained from P and the pedaling force Fs obtained from the stepping stroke amount S, and the composite pedaling force Fps, that is, the target deceleration G may temporarily increase to give the driver a sense of incompatibility ( (See FIG. 7).

  On the other hand, in this embodiment, when the pedal is returned, as shown in FIG. 17, the rate of change of the pedaling force based on the master cylinder pressure is limited by limiting the rate of decrease of the contribution α to the rate of change when the pedal is depressed. By moving closer, the shift of the pedaling force Fp calculated from the master cylinder pressure P and the pedaling force Fs determined from the master cylinder pressure P when shifting from the master cylinder pressure P priority to the pedaling stroke amount S is reduced. It is possible to suppress a temporary increase in the combined pedaling force Fps at the time of return, that is, the target deceleration G.

  Here, the deviation increases as the return speed of the brake pedal 1 increases. However, in this embodiment, the faster the return speed of the brake pedal 1, the greater the restriction on the reduction rate of the contribution degree α during the return. , And increase in deviation can be prevented. As a result, it is possible to calculate an appropriate target deceleration G according to the driver's brake operation at any stepping speed.

  Further, with respect to the relationship between the master cylinder pressure P and the stepping stroke amount S used when setting the relationship between the master cylinder pressure P and the contribution degree α, the larger the current stepping stroke amount S, that is, the current stepping stroke amount S is. As the current stepping stroke amount gain S is larger than the reference stepping stroke amount S corresponding to the master cylinder pressure P, the pedaling force Fs (target deceleration G and the target deceleration G) obtained by the stepping stroke amount S in the transition period is larger. The difference between the synonym) and the pedaling force Fp (synonymous with the target deceleration G) obtained by the master cylinder pressure P increases. On the other hand, in this embodiment, in this embodiment, the larger the deviation from the reference of the stepping stroke amount S, the larger the limit of the rate of decrease of the contribution α when the pedal is returned, thereby increasing the deviation. Can be prevented. As a result, it is possible to calculate an appropriate target deceleration G according to the driver's brake operation at any stepping speed.

FIG. 18 shows a time chart example. As shown in this time chart example, the pedaling force Fp based on the master cylinder pressure and the pedaling force Fs based on the stepping stroke amount S are changed by limiting the decreasing rate of the contribution degree α when the pedal is returned and slowing down the decreasing rate. As the speed approaches, the temporary deceleration of the target deceleration G can be suppressed.
Other configurations and operational effects are the same as in the above embodiment.

1 is a schematic diagram showing a circuit configuration according to a first embodiment of the present invention. It is a figure explaining the process of the brake controller which concerns on 1st Embodiment based on this invention. It is a figure which shows the relationship between the depression stroke amount S and the depression force Fs which concern on embodiment based on this invention. It is a figure which shows the relationship between the master cylinder pressure P and the pedal effort Fp which concern on embodiment based on this invention. It is a figure which shows the relationship between the master cylinder pressure P and contribution coefficient (alpha) which concern on embodiment based on this invention. It is a figure which shows the relationship between the composite pedaling force Fps and target deceleration G which concern on embodiment based on this invention. It is a schematic diagram explaining the raise of the target deceleration temporarily. It is a schematic diagram explaining the effect | action which concerns on 1st Embodiment based on this invention. It is a figure which shows the example of a time chart which concerns on 1st Embodiment based on this invention. It is a schematic diagram explaining the effect | action in another structure based on 1st Embodiment based on this invention. It is a figure which shows the example of a time chart in another structure based on 1st Embodiment based on this invention. It is a figure explaining the process of the brake controller which concerns on 2nd Embodiment based on this invention. It is a figure which shows the relationship between the amount of depression strokes, and a master cylinder pressure. It is a schematic diagram explaining the effect | action which concerns on 2nd Embodiment based on this invention. It is a figure which shows the example of a time chart which concerns on 2nd Embodiment based on this invention. It is a figure explaining the process of the brake controller which concerns on 3rd Embodiment based on this invention. It is a schematic diagram explaining the effect | action which concerns on 2nd Embodiment based on this invention. It is a figure which shows the example of a time chart which concerns on 2nd 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 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 Stepping stroke amount P Master cylinder pressure α Contribution G Target deceleration Fs Stepping force Fp based on stepping stroke amount Stepping force Fps based on master cylinder pressure Composite pedaling force Fpsmin Minimum value

Claims (3)

A master cylinder that outputs a master cylinder pressure according to the depression stroke of the driver's brake pedal, and a wheel cylinder that calculates the target deceleration based on the master cylinder pressure and the depression stroke amount of the brake pedal so that the target deceleration is obtained. A braking control means for controlling the braking force of the braking force control device, wherein the degree of contribution of the master cylinder pressure when calculating the target deceleration is set so as to increase as the master cylinder pressure increases,
The braking control means includes an increase limiting means for limiting a temporary increase of the target deceleration during the return of the brake pedal ,
The braking force control device according to claim 1, wherein when the target deceleration is estimated to increase or increase while the brake pedal is being returned, the increase limiting unit limits the increase of the target deceleration . 2. The braking force control apparatus according to claim 1 , wherein the increase limiting means limits the increase by maintaining the target deceleration at a constant value. The rise limiting means, when estimated that the target deceleration during the return of the brake pedal is or rises increases, according to claim 1, characterized in that to limit the increase in the target deceleration by fixing the contribution Braking force control device.

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