JP2008024142A - Braking force control device - Google Patents

Abstract

An object of the present invention is to provide a braking force control device that effectively suppresses pitching during braking by braking force control.
A braking force control apparatus (1) for controlling a braking force acting on a vehicle based on a braking operation by a driver, comprising braking force increasing speed means (3, 5) for determining an increasing speed of the braking force. When the braking force increasing speed obtained by the increasing speed means 3 and 5 is within a predetermined increasing speed range set based on the resonance frequency in the pitching direction of the vehicle, the braking force increasing speed is out of the predetermined increasing speed range. And controlling the braking force.
[Selection] Figure 1

Description

  The present invention relates to a braking force control device that controls a braking force acting on a vehicle based on a braking operation by a driver.

When the vehicle is braked suddenly by a brake operation by the driver, load movement occurs on the front side of the vehicle, which may cause a large pitching in which the front side sinks and the rear side rises. In such a case, the vehicle occupant feels uncomfortable and the riding comfort decreases. Therefore, various methods for suppressing such pitching have been proposed. In the braking force control device described in Patent Literature 1, pitching is suppressed by reducing the braking force of the front wheels in accordance with the pitch angular velocity (pitching state quantity) estimated based on the deceleration of the vehicle. In particular, in this braking force control device, the amount of decrease in the braking force of the front wheels is increased when the pitching state amount is large, compared to when it is small.
JP 2002-29397 A

  The coefficient of friction between the tire and the road surface increases as the vehicle speed decreases, and is highest immediately before the vehicle stops. Therefore, when the vehicle is suddenly braked while running at a walking speed (very low speed), a very large braking acceleration is generated in the vehicle, and the deceleration of the vehicle increases. Due to this large deceleration, the pitch angle of the vehicle becomes very large, resulting in excessive pitching. When such an excessive pitching occurs, the effect of suppressing the excessive pitching cannot be sufficiently obtained only by reducing the braking force of the front wheels as in the above-described braking force control device.

  Then, this invention makes it a subject to provide the braking force control apparatus which suppresses the pitching at the time of braking effectively by braking force control.

  A braking force control device according to the present invention is a braking force control device that controls a braking force that acts on a vehicle based on a braking operation by a driver, and includes a braking force increase speed unit that determines an increase rate of the braking force, When the braking force increasing speed obtained by the braking force increasing speed means falls within a predetermined increasing speed range set based on the resonance frequency in the pitching direction of the vehicle, the braking force increasing speed is out of the predetermined increasing speed range. The braking force is controlled.

  In this braking force control device, the braking force increasing speed means obtains the braking force increasing speed. When the deceleration (braking force increasing speed) generated by the braking force in the longitudinal direction of the vehicle coincides with the resonance frequency in the pitching direction of the vehicle, the load in the longitudinal direction of the vehicle fluctuates and the pitching of the vehicle overshoots. In addition, excessive pitching occurs in the vehicle. Since the resonance frequency in the pitching direction is determined by the vehicle, the range of the braking force increase speed (deceleration) in which excessive pitching may occur can be set based on the vehicle pitching resonance frequency. Therefore, in the braking force control device, when the braking force increasing speed is within a predetermined increasing speed range in which excessive pitching may occur (that is, when the pitching resonance frequency is reached), the braking force increasing speed is increased. The braking force is controlled so as to be out of the predetermined increase speed range. When the braking force increase speed is outside the predetermined increase speed range, resonance in the pitching direction of the vehicle is not suppressed or generated, and pitching during braking can be effectively suppressed. As a result, the vehicle occupant is not subject to discomfort due to excessive pitching, and the riding comfort is improved.

  The braking force increasing speed is an increasing speed of various parameters in the braking system from the brake pedal to which the operation by the driver is input to the wheel that outputs the braking force, and the deceleration of the vehicle generated in the vehicle by the braking force. Shall also be included. The braking force increase speed means may be a means for directly detecting the braking force increase speed (deceleration) by a sensor, or a value related to the braking force (for example, master cylinder hydraulic pressure, brake pedal depression force, brake pedal Stroke) may be detected, and the braking force increase speed may be obtained by calculation from the detected value.

  The braking force control apparatus according to the present invention may be configured to control the braking force so that the braking force increase speed increases when the braking force increase speed falls within a predetermined increase speed range.

  In this braking force control apparatus, when the braking force increase speed falls within a predetermined increase speed range, the braking force is controlled so that the braking force increase speed is increased to be outside the predetermined increase speed range. In this way, when the braking force is increased to increase the braking force increase speed, the pitching is effectively suppressed while ensuring a large braking force (and hence deceleration) for the driver's braking operation. Can do.

  The braking force control apparatus of the present invention may be configured to control the braking force so that the braking force increase rate becomes smaller when the braking force increase rate falls within a predetermined increase rate range.

  In this braking force control device, when the braking force increase speed falls within a predetermined increase speed range, the braking force is controlled so that the braking force increase speed is reduced to be out of the predetermined increase speed range. Thus, even when the braking force is decreased in order to reduce the braking force increase speed, the pitching can be effectively suppressed.

  The braking force control device of the present invention includes vehicle speed detection means for detecting the vehicle speed, and the braking force is increased so that the braking force increase speed is out of the predetermined increase speed range when the vehicle speed detected by the vehicle speed detection means is equal to or lower than the predetermined vehicle speed. It is good also as a structure which controls.

  In this braking force control device, the vehicle speed is detected by the vehicle speed detection means. The braking force control device controls the braking force so that the braking force increase speed is out of the predetermined increase speed range when the vehicle speed is equal to or lower than the predetermined vehicle speed and the braking force increase speed is within the predetermined increase speed range. . Since the coefficient of friction between the tire and the road surface increases as the vehicle speed decreases, a very large deceleration occurs in the vehicle when braking during low-speed traveling, resulting in excessive pitching. That is, there is a possibility that a larger pitching occurs at a lower speed. The predetermined vehicle speed is set in consideration of the relationship between the friction coefficient between the tire and the road surface and the vehicle speed, and is a vehicle speed threshold value for determining a low speed range in which a large pitching may occur during braking. Therefore, in this braking force control device, the braking force control is performed only at a low speed at which a large pitching may occur. Therefore, the braking force control for suppressing the pitching is not performed in an unnecessary scene.

  The present invention can effectively suppress pitching during braking by controlling the braking force so that the braking force increase speed does not coincide with the resonance frequency in the pitching direction of the vehicle.

  Embodiments of a braking force control device according to the present invention will be described below with reference to the drawings.

  In the present embodiment, the braking force control device according to the present invention is applied to a braking force control device that can arbitrarily control a braking force (brake hydraulic pressure) with respect to a driver's braking operation. The braking force control apparatus according to the present invention changes the braking force by controlling the hydraulic pressure of the wheel cylinder of each wheel by a brake actuator. In this embodiment, there are two embodiments due to the difference in hydraulic control (braking force control) for suppressing pitching, and the first embodiment is a mode for suppressing pitching by pressurization control, The second embodiment is a mode in which pitching is suppressed by pressure reduction control. Note that the braking force control device may be a device incorporated as a part of a system such as vehicle behavior stabilization, or may be a single device.

  With reference to FIGS. 1-3, the braking force control apparatus 1 which concerns on 1st Embodiment is demonstrated. FIG. 1 is a configuration diagram of a braking force control apparatus according to the present embodiment. FIG. 2 is a graph showing temporal changes in the master cylinder pressure and the wheel cylinder pressure, where (a) is a case where the boosting speed is lower than the boosting speed range corresponding to the vehicle pitching resonance frequency (in the case of normal braking). b) is the case where the boosting speed is within the boosting speed range corresponding to the vehicle pitching resonance frequency (in the case of sudden braking), and (c) is added when the boosting speed is within the boosting speed range corresponding to the vehicle pitching resonance frequency. This is a case where pressure control is performed, and (d) is a case where pressure reduction control is performed when the pressure increase speed is within the pressure increase speed range corresponding to the vehicle pitching resonance frequency. FIG. 3 is a graph showing the change over time in the boosting speed of the master cylinder, where (a) is when the boosting speed is lower than the boosting speed range corresponding to the vehicle pitching resonance frequency (in the case of normal braking), (b) Is when the boosting speed is within the boosting speed range corresponding to the vehicle pitching resonance frequency (in the case of sudden braking).

  The braking force control device 1 normally controls the braking force according to the driver's braking operation. Furthermore, when it is predicted that excessive pitching has occurred, the braking force control apparatus 1 controls the braking force so that the braking force increase rate is increased in order to suppress pitching. For this purpose, the braking force control device 1 includes wheel speed sensors 2A, 2B, 2C, 2D, a master cylinder pressure sensor 3, a brake actuator 4, and an ECU [Electronic Control Unit] 5. In the present embodiment, the processing in the wheel speed sensors 2A, 2B, 2C, 2D and the ECU 5 corresponds to the vehicle speed detecting means described in the claims, and the processing in the master cylinder pressure sensor 3 and the ECU 5 is claimed. This corresponds to the braking force increasing speed means described in the range.

  Wheel speed sensors 2A, 2B, 2C, and 2D are sensors that are provided in each wheel and detect the rotational speed of the wheel. The wheel speed sensors 2A, 2B, 2C and 2D detect the rotational speed of the wheel and transmit the detected value to the ECU 5 as a wheel speed signal.

  The master cylinder pressure sensor 3 is a sensor that is provided in the master cylinder MC and detects the hydraulic pressure of the master cylinder MC. The master cylinder pressure sensor 3 detects the master cylinder pressure, and transmits the detected value to the ECU 5 as a hydraulic pressure signal. The master cylinder pressure indicates the amount of brake operation by the driver because the pedal effort of the brake pedal BP is amplified by the brake booster BB and the amplified pedal effort is converted by the master cylinder MC. In the case of normal control, a braking force corresponding to the driver's brake operation is generated, so that a braking force corresponding to the master cylinder pressure is generated.

  The brake actuator 4 is provided on a hydraulic pipe that connects the master cylinder MC and the wheel cylinders WCA, WCB, WCC, WCD of each wheel, and the hydraulic pressure from the master cylinder MC is input to the wheel cylinders WCA, WCB, WCC, It is an actuator that adjusts the hydraulic pressure output to the WCD. The brake actuator 4 operates the actuator in accordance with the control current from the ECU 5 to generate predetermined hydraulic pressures in the wheel cylinders WCA, WCB, WCC, WCD, respectively.

  The ECU 5 is an electronic control unit that includes a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and performs overall control of the braking force control apparatus 1. The ECU 5 receives detection signals from the sensors 2A, 2B, 2C, 2D, 3 at regular intervals, and controls the brake actuator 4 based on the detection signals.

  The ECU 5 calculates the wheel speed of each wheel from the detected value indicated by the wheel speed signal of each wheel. Further, the ECU 5 calculates the vehicle body speed from the wheel speed of each wheel. Further, the ECU 5 calculates the pressure increase speed of the master cylinder from the change of the master cylinder pressure indicated by the oil pressure signal at regular intervals. This pressure increase speed corresponds to an increase speed of the brake operation amount by the driver. In the case of normal control, a braking force corresponding to the driver's braking operation is generated, so this pressure increase speed also corresponds to an increasing speed of the braking force.

  The ECU 5 determines whether the vehicle body speed is lower than the low speed determination vehicle body speed at regular time intervals. The low speed determination vehicle body speed is a vehicle speed threshold value for determining a low speed range in which large pitching may occur during braking, and is, for example, several km / h, which is about the walking speed. The low speed determination vehicle body speed is set in advance by experiments and simulations in consideration of the relationship between the friction coefficient between the tire and the road surface and the vehicle speed. In the determination of whether or not the vehicle speed is low, a vehicle speed lower than the low speed determination vehicle body speed is determined as a low speed while the vehicle is running, except when the vehicle speed is 0 km / h.

  In the ECU 5, when the vehicle body speed is lower than the low speed determination vehicle body speed, it is determined whether or not the boost speed of the master cylinder is within the range between the lower limit boost speed LV and the upper limit boost speed HV (see FIG. 3). The range between the lower limit boosting speed LV and the upper limit boosting speed HV is the range of the boosting speed (and hence the braking force increasing speed) of the master cylinder in which excessive pitching may occur. If the deceleration generated by the braking force (braking force increasing speed) matches the vehicle pitching resonance frequency, excessive pitching occurs in the vehicle. Since the vehicle pitching resonance frequency is determined by the vehicle, the braking force increase speed at which excessive pitching may occur can be set from the vehicle pitching resonance frequency. Therefore, the lower limit boosting speed LV and the upper limit boosting speed HV are set on the lower limit side and the upper limit side, respectively, in order to ensure a certain determination range around the boosting speed corresponding to the vehicle pitching resonance frequency determined by the vehicle.

  In the case of normal braking, the master cylinder pressure MP1 increases with a relatively gentle slope as shown in FIG. 2 (a), and the master cylinder pressure increase speed MV1 is higher than the lower limit pressure increase speed LV as shown in FIG. 3 (a). Get smaller. In this case, the deceleration generated by the braking force does not coincide with the vehicle pitching resonance frequency, so that a large pitching that causes the passenger to feel uncomfortable does not occur. However, in the case of sudden braking, the master cylinder pressure MP2 increases with a steep slope as shown in FIG. 2 (b), and the master cylinder boosting speed MV2 is equal to the lower limit boosting speed LV as shown in FIG. 3 (b). It falls within the range of the upper limit boosting speed HV. In this case, the deceleration generated by the braking force coincides with the vehicle pitching resonance frequency, and excessive pitching that causes the passenger to feel uncomfortable occurs.

  When the vehicle body speed is lower than the low speed determination vehicle body speed, or when the boosting speed of the master cylinder is outside the range between the lower limit boosting speed LV and the upper limit boosting speed HV, the ECU 5 sets the reference hydraulic pressure as the target hydraulic pressure. The reference hydraulic pressure is a master cylinder pressure corresponding to the driver's brake operation.

  When the vehicle body speed is lower than the low-speed determination vehicle body speed and the boost speed of the master cylinder is within the range between the lower limit boost speed LV and the upper limit boost speed HV, the ECU 5 uses a hydraulic pressure obtained by adding the pressurized hydraulic pressure to the reference hydraulic pressure as the target hydraulic pressure. Set. The pressurized hydraulic pressure increases the wheel cylinder pressure from the master cylinder pressure to increase the wheel cylinder pressure increasing speed (and thus the braking force increasing speed) so that the braking force increasing speed does not coincide with the vehicle pitching resonance frequency. For hydraulics. The pressurized hydraulic pressure may be set in advance as a constant amount in consideration of the speed range width between the lower limit boost speed LV and the upper limit boost speed HV, or may be variable based on the difference between the master cylinder pressure and the upper limit boost speed HV. It may be set as a quantity.

  When the target hydraulic pressure is the reference hydraulic pressure, as shown in FIG. 2A, the wheel cylinder pressure WP1 is the same as the master cylinder pressure MP1, and increases with the same gradient as the master cylinder pressure MP1. When the target hydraulic pressure is (reference hydraulic pressure + pressurized hydraulic pressure), as shown in FIG. 2 (c), the wheel cylinder pressure WP2 is pressurized from the master cylinder pressure MP2 and increases at a steeper slope than the master cylinder pressure MP2. To do. As a result, the braking force increasing speed becomes larger than the master cylinder pressure increasing speed and exceeds the vehicle pitching resonance frequency.

  When the target hydraulic pressure is set, the ECU 5 sets a target current for operating the brake actuator 4 so as to reach the target hydraulic pressure. Then, the ECU 5 supplies a control current to the brake actuator 4 so that the target current is obtained.

  The operation of the braking force control device 1 will be described with reference to FIG. In particular, the processing in the ECU 5 will be described along the flowchart of FIG. FIG. 4 is a flowchart showing a process flow in the ECU according to the first embodiment.

  Each wheel speed sensor 2A, 2B, 2C, 2D detects the rotational speed of each wheel and transmits each wheel speed signal to the ECU 5. The master cylinder pressure sensor 3 detects the hydraulic pressure of the master cylinder MC and transmits a hydraulic pressure signal to the ECU 5.

  At regular intervals, the ECU 5 receives wheel speed signals from the wheel speed sensors 2A, 2B, 2C, 2D, calculates the wheel speed of each wheel, and further calculates the vehicle speed (S1). Further, the ECU 5 receives a hydraulic pressure signal from the master cylinder pressure sensor 3 and calculates the pressure increase speed of the master cylinder (S2).

  The ECU 5 determines whether the vehicle body speed is lower than the low speed determination vehicle body speed (S3). When it is determined in S3 that the vehicle body is lower than the low speed determination vehicle body speed, the ECU 5 determines whether or not the boosting speed of the master cylinder is higher than the lower limit boosting speed and lower than the upper limit boosting speed (S4).

  When it is determined in S4 that the boosting speed of the master cylinder is higher than the lower limit boosting speed and lower than the upper limit boosting speed (that is, when it is predicted that excessive pitching will occur in the vehicle), the ECU 5 sets the target hydraulic pressure (master cylinder pressure). (+ Pressurized hydraulic pressure) is set, and a control current is supplied to the brake actuator 4 so as to reach the target hydraulic pressure (S5). Then, the brake actuator 4 operates according to the control current, and generates a hydraulic pressure corresponding to the target hydraulic pressure in the wheel cylinders WCA, WCB, WCC, WCD of each wheel. As a result, in the wheel cylinders WCA, WCB, WCC, and WCD of each wheel, the hydraulic pressure is increased from the master cylinder pressure, and the pressure increase speed is greater than the pressure increase speed of the master cylinder MC. Therefore, the braking force increase speed (vehicle deceleration) also increases, exceeds the vehicle pitching resonance frequency, and excessive pitching does not occur in the vehicle. In this case, the vehicle is not excessively pitched as shown in FIG. 6 (a), and the vehicle's pitching is suppressed as much as possible as shown in FIG. 6 (b).

  If it is determined in S3 that the vehicle body speed is greater than or equal to the low vehicle speed, or if it is determined in S4 that the boosting speed of the master cylinder is less than the lower limit boosting speed or greater than the upper limit boosting speed (that is, if excessive pitching does not occur in the vehicle) When predicted, the ECU 5 sets the master cylinder pressure as the target hydraulic pressure, and supplies a control current to the brake actuator 4 so as to reach the target hydraulic pressure (S6). Then, the brake actuator 4 operates according to the control current, and generates a hydraulic pressure corresponding to the target hydraulic pressure in the wheel cylinders WCA, WCB, WCC, WCD of each wheel. As a result, in the wheel cylinders WCA, WCB, WCC, and WCD of each wheel, the hydraulic pressure becomes the master cylinder pressure, and the pressure increase speed becomes equal to the pressure increase speed of the master cylinder MC.

  According to this braking force control device 1, when it is predicted that excessive pitching will occur in the vehicle, the pressure increase of the wheel cylinder is further increased by applying pressure to the master cylinder pressure, and the braking force increasing speed is determined by the vehicle pitching resonance frequency. By deviating from the above, resonance in the pitching direction of the vehicle is suppressed or not generated, and pitching can be effectively suppressed. As a result, the vehicle occupant is not subject to discomfort due to excessive pitching, and the riding comfort is improved.

  Moreover, in the braking force control apparatus 1, since brake hydraulic pressure is pressurized in order to suppress pitching, a braking force larger than usual can be ensured and sufficient deceleration can be generated for the driver's braking operation. Further, since the braking force control device 1 performs the braking force control for suppressing the pitching only at the time of low speed traveling, the unnecessary braking force control is not performed in the vehicle speed range where the excessive pitching does not occur.

  With reference to FIGS. 1-3, the braking force control apparatus 11 which concerns on 2nd Embodiment is demonstrated. Note that the braking force control device 11 is given the same reference numeral for the same configuration as the braking force control device 1 according to the first embodiment, and a description thereof is omitted.

  Compared with the braking force control device 1, the braking force control device 11 controls the braking force so that the braking force increase rate becomes smaller in order to suppress pitching. Therefore, in the braking force control device 11, a part of the processing in the ECU and the operation of the brake actuator corresponding to the part of the processing are different from the braking force control device 1. The braking force control device 11 includes wheel speed sensors 2A, 2B, 2C, 2D, a master cylinder pressure sensor 3, a brake actuator 4, and an ECU 15.

  The ECU 15 differs from the ECU 5 according to the first embodiment only in the target oil pressure setting process when suppressing pitching. Specifically, when the vehicle body speed is lower than the low speed determination vehicle body speed and the boosting speed of the master cylinder is within the range between the lower limit boosting speed LV and the upper limit boosting speed HV, the ECU 15 changes the reduced hydraulic pressure from the reference hydraulic pressure as the target hydraulic pressure. Set the subtracted hydraulic pressure. The reduced hydraulic pressure reduces the wheel cylinder pressure from the master cylinder pressure to reduce the wheel cylinder pressure increasing speed (and hence the braking force increasing speed) so that the braking force increasing speed does not coincide with the vehicle pitching resonance frequency. For hydraulics. The reduced hydraulic pressure may be set in advance as a constant amount in consideration of the speed range between the lower limit boost speed LV and the upper limit boost speed HV, or as a variable quantity based on the difference between the master cylinder pressure and the lower limit boost speed LV. It may be set.

  When the target oil pressure is (reference oil pressure-reduced pressure oil pressure), as shown in FIG. 2D, the wheel cylinder pressure WP3 is reduced from the master cylinder pressure MP2 and increases with a gentler gradient than the master cylinder pressure MP2. As a result, the braking force increasing speed becomes smaller than the master cylinder pressure increasing speed and is lower than the vehicle pitching resonance frequency.

  The operation of the braking force control device 11 will be described with reference to FIG. In particular, the processing in the ECU 15 will be described along the flowchart of FIG. FIG. 5 is a flowchart showing a flow of processing in the ECU according to the second embodiment.

  The wheel speed sensors 2A, 2B, 2C, 2D and the master cylinder pressure sensor 3 perform the same operation as in the first embodiment. Further, the ECU 15 performs the same processes as S1 to S4 in the first embodiment for the processes from S11 to S14.

  When it is determined in S14 that the boosting speed of the master cylinder is higher than the lower limit boosting speed and lower than the upper limit boosting speed, the ECU 15 sets (master cylinder pressure minus reduced pressure hydraulic pressure) as the target hydraulic pressure so that the target hydraulic pressure is reached. A control current is supplied to the brake actuator 4 (S15). Then, the brake actuator 4 operates according to the control current, and generates a hydraulic pressure corresponding to the target hydraulic pressure in the wheel cylinders WCA, WCB, WCC, WCD of each wheel. As a result, in the wheel cylinders WCA, WCB, WCC, and WCD of each wheel, the hydraulic pressure is reduced from the master cylinder pressure, and the pressure increase speed becomes smaller than the pressure increase speed of the master cylinder MC. As a result, the braking force increase speed (vehicle deceleration) also becomes smaller, lower than the vehicle pitching resonance frequency, and excessive pitching does not occur in the vehicle. In this case as well, as in the first embodiment, the vehicle is not pitched excessively as shown in FIG. 6A, and the vehicle pitching is suppressed as much as possible as shown in FIG. 6B. It becomes a state.

  When it is determined at S13 that the vehicle body speed is greater than or equal to the low vehicle speed determination, or when it is determined at S14 that the boosting speed of the master cylinder is equal to or lower than the lower limit boosting speed or greater than or equal to the upper limit boosting speed, the ECU 15 The same processing is performed, and the brake actuator 4 performs the same operation as in the first embodiment.

  According to this braking force control device 11, when it is predicted that excessive pitching will occur in the vehicle, the pressure increase rate of the wheel cylinder is reduced by reducing the pressure against the master cylinder pressure, and the braking force increase rate is determined from the vehicle pitching resonance frequency. By deviating, the same effect as the first embodiment can be obtained. Also, the braking force control device 11 performs the braking force control for suppressing the pitching only at the time of low-speed traveling, and thus has the same effect as the first embodiment.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the braking force is changed by arbitrarily controlling the brake hydraulic pressure by the brake actuator. However, other means such as pressurizing the brake hydraulic pressure like a brake assist may be used. Further, in the present embodiment, the configuration is such that the hydraulic pressure of the wheel cylinder is controlled by the brake actuator in order to change the braking force, but other configurations such as changing the hydraulic pressure of the master cylinder by the brake booster may be used.

  In the present embodiment, the master cylinder hydraulic pressure is detected as the braking force increase speed, and the master cylinder pressure increase speed is calculated. However, other amounts related to the braking force such as the stroke of the brake pedal and the pedaling force are detected by the sensor. It is good also as a structure which detects this, and calculates the change speed, or it is good also as a structure which detects directly the increase speed of the quantity regarding a braking force with a sensor.

  In this embodiment, the braking force control is performed to suppress the pitching when the vehicle is traveling at a low speed and the brake boosting speed is within the range corresponding to the vehicle pitching resonance frequency. When pitching occurs, braking force control for suppressing pitching may be performed in other vehicle speed regions.

It is a block diagram of the braking force control apparatus which concerns on this Embodiment. It is a graph which shows the time change of a master cylinder pressure and a wheel cylinder pressure, (a) is a case where a pressure increase speed is lower than the pressure increase speed range corresponding to a vehicle pitching resonance frequency (in the case of normal braking), (b) is a pressure increase When the speed is within the boosting speed range corresponding to the vehicle pitching resonance frequency (in the case of sudden braking), pressurization control is performed when (c) is within the boosting speed range corresponding to the vehicle pitching resonance frequency. (D) is a case where the pressure reduction control is performed when the pressure increase speed is within the pressure increase speed range corresponding to the vehicle pitching resonance frequency. It is a graph which shows the time change of the boosting speed of a master cylinder, (a) is a case where a boosting speed is lower than the boosting speed range corresponding to a vehicle pitching resonance frequency (in the case of normal braking), (b) is a boosting speed. This is the case (in the case of sudden braking) within the pressure increase speed range corresponding to the vehicle pitching resonance frequency. It is a flowchart which shows the flow of a process in ECU which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process in ECU which concerns on 2nd Embodiment. It is a schematic diagram which shows the state of the pitching direction of a vehicle, (a) is a case where excessive pitching generate | occur | produces, (b) is a case where pitching is suppressed by the braking force control apparatus which concerns on this Embodiment. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 ... Braking force control apparatus, 2A, 2B, 2C, 2D ... Wheel speed sensor, 3 ... Master cylinder pressure sensor, 4 ... Brake actuator, 5, 15 ... ECU

Claims (4)

A braking force control device for controlling a braking force acting on a vehicle based on a braking operation by a driver,
A braking force increasing speed means for obtaining an increasing speed of the braking force;
When the braking force increasing speed obtained by the braking force increasing speed means falls within a predetermined increasing speed range set based on the resonance frequency in the pitching direction of the vehicle, the braking force increasing speed is out of the predetermined increasing speed range. A braking force control device characterized by controlling braking force.   The braking force control apparatus according to claim 1, wherein the braking force is controlled so that the braking force increase speed increases when the braking force increase speed falls within a predetermined increase speed range.   2. The braking force control apparatus according to claim 1, wherein the braking force is controlled so that the braking force increase speed becomes smaller when the braking force increase speed falls within a predetermined increase speed range. 3. Vehicle speed detection means for detecting the vehicle speed,
The braking force is controlled such that the braking force increase speed is outside a predetermined increasing speed range when the vehicle speed detected by the vehicle speed detecting means is equal to or lower than a predetermined vehicle speed. The braking force control apparatus described in the item.

Images