JP4729960B2 - Friction braking device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking device, and more particularly to a friction braking device that controls a braking force by pressing a friction material against a rotating member that rotates together with a wheel and controlling the pressing force.

  A friction braking device for a vehicle such as an automobile generally has a rotating member such as a brake rotor that rotates together with a wheel, a friction material such as a brake pad, a caliper that accommodates and supports the friction material, and presses the caliper to press the friction material. A pressing unit that presses the rotating member; and a control unit that controls the pressing of the pressing unit based on at least a braking operation of the driver. In this case, the friction material is accommodated and supported by the caliper with a predetermined clearance so that the friction material can move freely in a direction approaching the rotating member and in a direction away from the caliper.

As one of such friction braking devices, as described in, for example, Patent Document 1 below, when the braking is started after the traveling direction of the vehicle is reversed, the friction material together with the rotating member moves relative to the caliper in the rotating direction. There is already known a friction braking device in which grease is applied to the contact surface between the friction material and the caliper in order to reduce a “cinch” croaking sound generated due to the displacement and the friction material hitting the caliper. Yes.
JP-A-9-303432

  According to the friction braking device as described above, when the braking is started after the traveling direction of the vehicle is reversed, compared with the friction braking device in which the reduction of the crumb noise is not applied to the contact surface between the friction material and the caliper. The impact of the friction material against the caliper can be reduced and the crumb noise can be reduced. However, the impact mitigation action of the grease decreases with the deterioration and wear of the grease, so the crumb noise is reliably reduced over a long period of time. There is a problem that you can not.

  The present invention has been made in view of the above-described problems in a conventional friction braking device in which a friction material is accommodated and supported by a caliper with a predetermined clearance, and the main problem of the present invention is that the traveling direction of a vehicle The kinetic energy when the friction material strikes the caliper is reduced by reducing the moving distance or moving speed when the friction material moves relative to the caliper in the rotation direction together with the rotating member at the start of braking after the reverse rotation By reducing the noise, it is possible to reliably reduce the clonk noise over a long period of time.

According to the present invention, the main problems described above are a rotating member that rotates together with a wheel, a friction material, a caliper that accommodates and supports the friction material with a predetermined clearance, and presses the friction material against the rotating member. In a vehicle friction braking device having pressing means and control means for controlling pressing of the pressing means based on at least a driver's braking operation, the control means has means for detecting the traveling direction of the vehicle. , by the rotary member before serial pressing means the friction member in the rotational direction with minimal pressing force sufficient to move relative to said caliper when the traveling direction of the vehicle is reversed wheel starts to rotate A friction braking device for a vehicle (configuration of claim 1), wherein the friction member is pressed against the rotating member, or a rotating member that rotates together with a wheel, a friction member, and a predetermined clearance. A caliper that accommodates and supports the friction material, a pressing device that presses the friction material against the rotating member, and a control device that controls the pressing of the pressing device based on at least the braking operation of the driver. In this friction braking device, the control means has means for detecting the traveling direction of the vehicle, and the reverse of the traveling direction of the vehicle is detected at the start of the first braking after the reverse of the traveling direction of the vehicle is detected. This is achieved by a vehicle friction braking device (structure of claim 7 ) characterized in that an increasing gradient of pressing force by the pressing means is made smaller than when braking is started when there is no braking.

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the vehicle is a vehicle on which an automatic transmission is mounted, and the control means is determined by the driver. When the braking operation is released by the driver after the reverse operation in the traveling direction of the vehicle is detected, the pressing by the pressing means is started (configuration of claim 2).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claim 1, the vehicle is a vehicle equipped with a manual transmission, and the control means is determined by the driver. It is comprised so that the press by the said press means may be started, when a clutch is engaged by the driver | operator after detecting the reverse operation of the advancing direction of a vehicle (structure of Claim 3).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration of claims 1 to 3, the control means has means for detecting the rotation of a wheel, It is comprised so that the press by the said press means may be started when rotation of the wheel to the direction where a direction reverses is detected (structure of Claim 4).

  Further, according to the present invention, in order to effectively achieve the main problems described above, in the configuration of claims 1 to 4, the pressing by the pressing means is continued for a preset time. (Structure of claim 5).

  According to the present invention, in order to effectively achieve the main problem described above, in the configuration of claim 5, the preset time of the rotating member after the traveling direction of the vehicle is reversed. The time is sufficient to move the friction material relative to the caliper in the rotation direction (configuration of claim 6).

According to the first aspect of the present invention, when the situation in which the traveling direction of the vehicle is reversed is detected, the friction material is pressed against the rotating member by the pressing means without the driver's braking operation. The friction material can be moved relative to the caliper in the direction of rotation of the rotating member after the traveling direction of the vehicle is reversed by applying a frictional force to the rotating member. When done, the friction material moves with the rotating member in the direction of rotation relative to the caliper, reducing the moving distance or moving speed, and reducing the kinetic energy when the friction material hits the caliper. Therefore, it is possible to reliably reduce the clonk noise over a long period of time.
According to the first aspect of the present invention, the pressing force pressing the friction material against the rotating member moves the friction material relative to the caliper in the rotation direction of the rotating member after the traveling direction of the vehicle is reversed. Since the minimum pressing force is sufficient, it is possible to prevent the friction material from being pressed against the rotating member by excessive pressing force and unnecessary braking force from being generated due to the pressing force, and the vehicle traveling direction. Thus, the friction material can be reliably moved relative to the caliper in the rotation direction of the rotating member after the reverse rotation.

  According to the second aspect of the present invention, the vehicle is a vehicle equipped with an automatic transmission, and when the driver releases the braking operation after detecting the reverse operation of the traveling direction of the vehicle by the driver. Since the pressing by the pressing means is started, it is possible to reduce the possibility that the pressing is unnecessarily started earlier than when the pressing by the pressing means is started when the reverse operation in the traveling direction of the vehicle is detected. In addition, when the braking operation is released, creep force acts on the drive wheels and rotation of the wheels starts to start pressing, so that the friction material is reliably relative to the caliper in the direction of rotation of the rotating member. Can be moved.

  Further, according to the configuration of claim 3, the vehicle is a vehicle equipped with a manual transmission, and when the driver engages the clutch after detecting the reverse operation of the traveling direction of the vehicle by the driver. Since the pressing by the pressing means is started, it is possible to reduce the possibility that the pressing is unnecessarily started earlier than when the pressing by the pressing means is started when the reverse operation in the traveling direction of the vehicle is detected. In the situation where the driving force is applied to the driving wheel due to the engagement of the clutch and the rotation of the wheel is highly likely to start, the pressing of the friction member is effectively performed, thereby rotating the rotating member in the rotation direction. Can be moved relative to the caliper.

  According to the fourth aspect of the present invention, since the pressing by the pressing means is started when the rotation of the wheel in the direction in which the traveling direction of the vehicle is reversed is detected, the friction between the friction material and the rotating member is The friction material can be reliably moved relative to the caliper in the direction of rotation of the rotating member after the traveling direction of the vehicle is reversed by the force, so that the friction material is removed when a braking operation is performed by the driver. The moving distance or moving speed when moving relative to the caliper in the rotation direction together with the rotating member can be reliably reduced, and the kinetic energy when the friction material strikes the caliper can be reliably reduced.

  Further, according to the configuration of the fifth aspect, since the pressing by the pressing means is continued for a preset time, the possibility that the pressing by the pressing means is continued unnecessarily for a long time is surely reduced. be able to.

  Further, according to the configuration of claim 6, the preset time is sufficient to move the friction material relative to the caliper in the rotational direction of the rotating member after the traveling direction of the vehicle is reversed. The friction material can be reliably moved relative to the caliper in the rotation direction of the rotating member after the traveling direction of the vehicle is reversed.

According to the seventh aspect of the present invention, the pressing means at the time of the first braking start after the reverse of the traveling direction of the vehicle is detected is compared with the time of the braking when the reverse of the traveling direction of the vehicle is not detected. Since the increase gradient of the pressing force due to is reduced, the movement when the friction material moves relative to the caliper in the rotation direction together with the rotating member at the start of the first braking after the reverse of the traveling direction of the vehicle is detected The speed can be reduced, and the kinetic energy when the friction material strikes the caliper can be reduced, thereby making it possible to reliably reduce the clonk noise over a long period of time.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of the first to seventh aspects, the means for detecting the traveling direction of the vehicle is configured to detect the traveling direction of the vehicle based on the shift position of the transmission. (Preferred embodiment 1)

  According to another preferred aspect of the present invention, in the configuration of claim 1 or 2 or the preferred aspect 1, the driver performs a braking operation when the amount of braking operation of the driver becomes equal to or less than a reference value. Is determined to be released (Preferred aspect 2).

  According to another preferred aspect of the present invention, in the configuration of claim 4 or preferred aspect 1 or 2, the means for detecting the rotation of the wheel is a wheel speed detecting means, and an average of all the wheels. It is comprised so that it may determine with the wheel having rotated, when a wheel speed is more than a reference value (preferred aspect 3).

  According to another preferred aspect of the present invention, in the configuration of claim 4 or preferred aspect 1 or 2 above, the means for detecting the rotation of the wheel is a wheel speed detecting means. It is comprised so that it may determine with the wheel having rotated, when wheel speed is more than a reference value (preferred aspect 4).

  According to another preferred aspect of the present invention, in the configuration of claim 5 or 6 or the preferred embodiments 1 to 4, the preset time is configured to be a preset constant time. (Preferred embodiment 5)

  According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 5 or 6 or the preferred aspects 1 to 4, the preset time is variable according to the vehicle speed so as to become shorter as the vehicle speed is higher. It is configured to be set (preferred aspect 6).

According to another preferred embodiment of the present invention, in the configuration of the above-described claims 1 to 6 or the preferred embodiments 1 to 6, the pressing force for pressing the friction material against the rotating member is a predetermined constant value. It is comprised so that it may be a pressing force (the preferable aspect 7).

According to another preferred aspect of the present invention, in the configuration of claim 7 , the control means is configured to reduce an increasing gradient of the pressing force by the pressing means over a predetermined time (preferred aspect 8). ).

  According to another preferred aspect of the present invention, in the configuration of the preferred aspect 8, the predetermined time is variably set according to the vehicle speed so as to be longer when the vehicle speed is low than when the vehicle speed is high. (Preferred embodiment 9)

According to another preferred aspect of the present invention, in the configuration of the above-mentioned claim 7 or the preferred aspect 8 or 9, when the vehicle speed is high when the vehicle speed is high, the degree of decrease in the increase gradient of the pressing force by the pressing means is low. It is configured to be variably set according to the vehicle speed so as to be lower than (preferred aspect 10).

According to another preferred aspect of the present invention, in the configuration of claim 7 or preferred aspects 8 to 10, the control means determines whether or not the braking operation of the driver is a sudden braking operation. It is determined that when the driver's braking operation is a sudden braking operation, the increase gradient of the pressing force by the pressing means is not reduced (preferable aspect 11).

  The present invention will now be described in detail with reference to a few preferred embodiments with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a first embodiment of a vehicle friction braking device according to the present invention applied to a vehicle equipped with an automatic transmission.

  In FIG. 1, reference numeral 10 denotes a rotor disk as a rotating member that rotates around a wheel axis 10A together with a wheel not shown. A caliper 12 is disposed at a position close to the outer edge of the rotor disk 10, and the caliper 12 can reciprocate in a direction perpendicular to the rotor disk 10 along the axis 10A. It is attached.

  The caliper 12 has a brake pad accommodating portion 14 that accommodates and supports a brake pad 16 as a friction material with a predetermined clearance. The brake pad 16 can move relative to the caliper 12 along the axis 10 </ b> A, and can move relative to the caliper 12 in the same direction as the rotation direction of the rotor disk 10 and in the opposite direction.

  The caliper 12 is driven by increasing / decreasing the pressure in the wheel cylinder 18 (wheel cylinder pressure) schematically shown in FIG. 1, and the wheel cylinder pressure is controlled by a hydraulic circuit 20. Although not shown in FIG. 1, the hydraulic circuit 20 includes a reservoir, an oil pump, various valve devices, and the like, and the wheel cylinder pressure is normally driven in accordance with the depression operation of the brake pedal 22 by the driver. The pressure is controlled by the electronic control unit 26 based on the pressure in 24, that is, the master cylinder pressure Pm, and is controlled as necessary regardless of the master cylinder pressure Pm.

  When the wheel cylinder pressure is increased, the caliper 12 is pressed toward the rotor disk 10, whereby the brake pad 16 is pressed against the rotor disk 10, and is controlled by the frictional force between the brake pad 16 and the rotor disk 10. Power is generated. Conversely, when the wheel cylinder pressure is reduced, the caliper 12 is driven in a direction away from the rotor disk 10 by the urging means not shown in the figure, thereby reducing the braking force. When the wheel cylinder pressure is reduced to the non-braking pressure, substantially no frictional force is generated between the brake pad 16 and the rotor disk 10, and thus no braking force is generated.

  Although not shown in the figure, the vehicle is a so-called AT vehicle equipped with an automatic transmission, and the driving force of the engine is transmitted to the propeller shaft via an automatic transmission including a torque converter and a transmission. Is transmitted to the left and right drive wheels via the differential and left and right axles, whereby the left and right drive wheels are rotationally driven.

  The electronic control unit 26 receives a signal indicating the master cylinder pressure Pm from the pressure sensor 28, and the wheel cylinder pressure of each wheel, that is, the braking pressure Pi (i = fl, fr) from the pressure sensor 30i (i = fl, fr, rl, rr). , Rl, rr), a signal indicating the shift position of the automatic transmission not shown in the figure from the shift position (SP) sensor 32, and a wheel speed sensor 34i (i = fl, fr, rl, rr) A signal indicating the wheel speed Vwi of each wheel is input.

  Although not shown in detail in FIG. 1, the electronic control unit 26 includes a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other by a bidirectional common bus and a drive circuit. It may be better.

  The electronic control unit 26 calculates a target braking pressure Pwti (i = fl, fr, rl, rr) of each wheel based on the master cylinder pressure Pm in a manner known in the art, and normally brakes each wheel. Control is performed so that the pressure Pi becomes the corresponding target braking pressure Pwti. On the other hand, the electronic control unit 26 applies a braking pressure to each wheel when a shift operation for reversing the traveling direction is performed after the braking of the vehicle is stopped, or when the braking operation is released by the driver after that. Pi is controlled to a preset braking pressure Pwo over a predetermined time Ta, whereby the brake pad 16 is moved relative to the caliper 12 in the rotational direction after the reverse rotation of the traveling direction of the rotor disk 10.

  Next, the braking force control routine in the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals. In FIG. 2, the flag Fa relates to whether or not the pressing force control is executed to prevent the generation of a cronk at the start of braking after reversing the traveling direction of the vehicle. It means that control is being executed. When the control according to the flowchart shown in FIG. 2 is started, the flag Fa is initialized by being set to 1 and then reset to 0 prior to step 10.

  First, at step 10, a signal indicating the master cylinder pressure Pm detected by the pressure sensor 28 is read, and at step 20, based on the master cylinder pressure Pm, a procedure known in the art is performed. Thus, the target braking pressure Pwti (i = fl, fr, rl, rr) of each wheel is calculated.

  In step 30, it is determined whether or not the flag Fa is 1, that is, whether or not the control of the pressing force for preventing the generation of a clonk noise at the start of braking after reversing the traveling direction of the vehicle is executed. If a negative determination is made, the process proceeds to step 60. If an affirmative determination is made, the process proceeds to step 40.

  In step 40, for example, whether or not the braking operation is being performed by the driver is determined by determining whether or not the master cylinder pressure Pm is equal to or greater than a reference value Pms (positive constant) for braking determination. If a negative determination is made, the process proceeds to step 100. If an affirmative determination is made, the flag Fa is reset to 0 in step 50, and then the process proceeds to step 130.

  In step 60, after the flag Fa is reset from 1 to 0, after the vehicle stops braking, the shift operation for reverse rotation of the traveling direction, that is, the shift operation from the forward gear to the reverse gear, or the shift from the reverse gear to the forward gear is performed. It is determined whether or not an operation has been performed. When a negative determination is made, the process proceeds to step 130, and when an affirmative determination is performed, the process proceeds to step 70.

  In step 70, the average value Vwa of the wheel speed Vwi of each wheel is calculated, and it is determined whether or not the average value Vwa of the wheel speed is equal to or greater than a reference value Vwo (positive constant) for determining wheel rotation. If a negative determination is made, the process proceeds to step 80. If an affirmative determination is made, the process proceeds to step 90.

  In step 80, for example, a determination is made as to whether or not the braking operation by the driver has been released by determining whether or not the master cylinder pressure Pm has become equal to or less than the reference value Pme of the braking operation release determination. If yes, the process proceeds to step 90. If a negative determination is made, the process proceeds to step 130.

  In step 90, the pressurization time Ta is calculated on the basis of the average value Vwa of the wheel speed so as to become shorter as the average value Vwa of the wheel speed becomes higher. In step 100, the flag Fa is set to 1, and The target braking pressure Pwti of each wheel is set to a preset braking pressure Pwo. The preset braking pressure Pwo is a pressure that generates a minimum pressing force sufficient to move the brake pad 16 relative to the caliper 12 in the rotational direction of the rotor disk 10 after the traveling direction of the vehicle is reversed. Is set.

  In step 110, it is determined whether or not the pressurization time Ta has elapsed since the start of pressurization with a preset braking pressure Pwo. If a negative determination is made, the process proceeds to step 130 as it is. When an affirmative determination is made, the flag Fa is reset to 0 in step 120 and the target braking pressure Pwti of each wheel is set to 0. Thereafter, in step 130, the braking pressure Pwi of each wheel is set. Control is performed to achieve the corresponding target braking pressure Pwti.

  Thus, according to the illustrated embodiment 1, it is determined in step 60 whether or not a shift operation for reversing the traveling direction has been performed after stopping the braking of the vehicle. In step 70, the wheel speed Vwi of each wheel is determined. It is determined whether or not the average value Vwa is equal to or greater than a reference value Vwo for determining the rotation of the wheel. In step 80, it is determined whether or not the braking operation by the driver has been released. When it is determined that the wheel is rotated later or the braking operation by the driver is released after that, the braking pressure of each wheel is determined in steps 90 to 130. Pi is controlled to a predetermined braking pressure Pwo over a predetermined time Ta.

  For example, FIG. 6 is a graph showing an example of braking force control in the first embodiment. As shown in FIG. 6, the vehicle stops due to braking deceleration at time t1, shift operation in reverse of the traveling direction is performed at time t2, and braking operation by the driver is released at time t3. If it is determined that the average value Vwa of the wheel speed is equal to or greater than the reference value Vwo for determining the rotation of the wheel at time t4, the braking pressure Pi of each wheel is determined for a predetermined time Ta from time t4 to time t5. It is controlled to a predetermined braking pressure Pwo.

  In the conventional friction braking device, as shown in FIG. 5A, when the vehicle stops due to braking, the brake pad 16 is calipered by the frictional force between the brake pad 16 and the rotor disk 10. 12, the distance between the side surface of the brake pad 16 and the side surface of the brake pad accommodating portion 14 on the lagging direction of the rotor disk 10 is increased. It continues even after the driver releases the braking operation.

  Thereafter, a shift operation is performed to reverse the direction of travel, and when the driver performs a braking operation while the vehicle is traveling, the friction between the brake pad 16 and the rotor disk 10 is shown in FIG. The brake pad 16 is moved relative to the caliper 12 in the rotational direction of the rotor disk 10 by the force, and the brake pad 16 strikes the side surface of the brake pad housing portion 14 as shown in FIG. As a result, a cronk sound is generated.

  On the other hand, according to the illustrated first embodiment, as shown in FIG. 4A, when the vehicle is stopped, the side surface of the brake pad 16 and the brake pad housing portion 14 on the delay side of the rotor disk 10 are delayed. Even if the distance from the side of the vehicle increases, a shift operation for reversing the traveling direction is performed thereafter, and it is determined that the wheel is rotating in the reversing direction of the traveling direction or that the braking operation by the driver is released. At that time, as shown in FIG. 4B, the brake pad 16 is pressed against the rotor disk 10 with a predetermined pressing force for a predetermined time, whereby the brake pad 16 is moved to the caliper 12. The brake pad 16 is moved in advance in the rotational direction of the rotor disk 10 in advance, and as shown in FIG. Distance between side surfaces of a brake pad housing 14 is reliably reduced.

  4 and 5, the white arrow indicates the pressing force against the caliper 12 due to the wheel cylinder pressure, the thin arrow indicates the rotational direction of the rotor disk 10, and the thick arrow indicates the rotor disk 10. The movement direction of the brake pad 16 by the frictional force between the brake pads 16 is shown.

  Therefore, according to the illustrated first embodiment, even if the driver performs a braking operation after the vehicle traveling direction is reversed, the brake pad 16 moves relative to the caliper 12 toward the rotational direction advance side of the rotor disk 10. Since the distance and speed of movement are reduced and the kinetic energy of the brake pad 16 in the rotational direction of the rotor disk 10 is reduced, the generation of a loud clonk sound caused by striking the side surface of the brake pad housing portion 14 is prevented. It can be effectively and reliably prevented, and this action is demonstrated without the need for grease that deteriorates over time or wears out over a long period of time. Can be prevented.

  In particular, according to the first embodiment shown in the drawing, steps 90 to 130 are not executed as soon as it is determined in step 60 that a shift operation for reversing the traveling direction has been performed after the vehicle has stopped braking. In step 70, it is determined that the shift operation for reversing the traveling direction has been performed after the braking of the vehicle is stopped. In step 70, it is determined that the wheel is rotating, or in step 80, the braking operation by the driver is released. Steps 90 to 130 are executed when the determination is made, so that each wheel in the situation where the wheel is not rotating even when the shift operation for reversing the traveling direction is performed or the braking operation by the driver is not released. Therefore, it is possible to reliably prevent the braking pressure Pi from increasing unnecessarily.

  Further, according to the illustrated embodiment 1, the predetermined pressurization time Ta is calculated according to the average value Vwa of the wheel speed so as to become shorter in step 90 as the average value Vwa of the wheel speed becomes higher. The predetermined pressurization time Ta can be set to an optimal value without excess or deficiency in accordance with the wheel speed at the start of the control of the pressing force for preventing the occurrence of the pressure.

  FIG. 3 is a flowchart showing a braking force control routine in the second embodiment of the vehicle friction braking apparatus according to the present invention. In FIG. 3, the flag Fb relates to whether or not the braking pressure increase suppression control is performed at the start of the first braking after the vehicle traveling direction is reversed. Means that it is running. Also, at the start of the control according to the flowchart shown in FIG. 3, the flag Fb is set to 1 prior to step 210 and then initialized to 0.

  In the second embodiment, when the electronic control unit 26 performs a shift operation for reversing the traveling direction after the braking of the vehicle is stopped, each wheel is operated when the braking operation is first performed by the driver thereafter. The increase in the kinetic energy of the brake pad 16 is suppressed when the brake pad 16 moves relative to the caliper 12 in the rotational direction of the rotor disk 10. This prevents the brake pad 16 from hitting the caliper 12 with high kinetic energy. The vehicle transmission to which the second embodiment is applied may be either an automatic transmission or a manual transmission.

  Next, a braking force control routine in the second embodiment will be described with reference to the flowchart shown in FIG. Note that the control according to the flowchart shown in FIG. 3 is also started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals.

  First, in step 110, a signal indicating the master cylinder pressure Pm detected by the pressure sensor 28 is read, and in step 220, the same procedure as in step 20 in the first embodiment is performed. The target braking pressure Pwti of each wheel is calculated.

  In step 230, for example, based on the rate of increase of the master cylinder pressure Pm, it is determined whether or not a sudden braking operation has been performed by the driver. If an affirmative determination is made, the flag Fb is set to 0 in step 240. After resetting, the process proceeds to step 360. When a negative determination is made, the process proceeds to step 250.

  In step 250, it is determined whether or not the flag Fb is 1, that is, whether or not the braking pressure increase suppression control is performed at the start of the first braking after the traveling direction of the vehicle is reversed. When a positive determination is made, the process proceeds to step 300, and when a negative determination is made, the process proceeds to step 260.

  In step 260, the same determination as in step 60 in the first embodiment is performed. If a negative determination is made, the process proceeds to step 360. If an affirmative determination is made, the process proceeds to step 270.

  In step 270, the same determination as in step 40 in the first embodiment is performed. When a negative determination is made, the process proceeds to step 360. When an affirmative determination is made, the process proceeds to step 280. The flag Fb is set to 1.

  In step 290, the vehicle speed V is increased so that the higher the vehicle speed V is within the range of the correction coefficient Kb greater than 0 and less than 1, the greater the vehicle speed V, and the lower the vehicle speed V, the longer the braking pressure increase suppression time Tb. Based on this, the correction coefficient Kb and the braking pressure increase suppression time Tb are calculated, and then the routine proceeds to step 360.

  In step 300, it is determined whether or not the suppression time Tb has elapsed since the time point when the suppression of the increase in braking pressure was started. If a negative determination is made, the process proceeds to step 320, where an affirmative determination is made. In this case, the previous value of the correction coefficient Kb is set to Kbf, ΔKb is set to a small positive constant, and the correction coefficient Kb is set to the sum of the previous value Kbf and the increment amount ΔKb.

In step 320, a temporary target braking pressure Pwtai of each wheel is calculated according to the following equation 1 as a deviation ΔPwti between the target braking pressure Pwti of each wheel and its previous value Pwtfi.
Pwtai = Pwtfi + KbΔPwti (1)

  In step 330, it is determined whether any of the provisional target braking pressures Pwti of each wheel is equal to or higher than the target braking pressure Pwti. If a negative determination is made, in step 340, the target braking pressure is determined. When Pwti is set to the provisional target braking pressure Pwtai and an affirmative determination is made, the flag Fb is reset to 0 in step 350, and in step 360 in step 130 in the first embodiment described above. The braking pressure of each wheel is controlled in the same manner as above.

  Thus, according to the illustrated second embodiment, in steps 260 and 270, it is determined whether or not the braking operation has been started by the driver after the shifting operation for reversing the traveling direction is performed after stopping the braking of the vehicle. When the braking operation is started by the driver after the vehicle has been braked, the correction coefficient Kb and the braking pressure increase suppression time Tb are calculated in step 290. In 360, the pressure increasing gradient of the braking pressure Pi of each wheel is suppressed for a predetermined time Ta.

  Therefore, according to the second embodiment shown in the figure, after the vehicle has stopped braking, a shift operation is performed to reverse the direction of travel, and then the driver performs the braking operation first so that the brake pad 16 moves in the direction of rotation of the rotor disk 10. The increase in the kinetic energy of the brake pad 16 when moving relative to the brake pad 16 is suppressed, and thereby, the brake pad 16 strikes the caliper 12 with high kinetic energy and the generation of the cronk sound resulting therefrom is effective. Can be prevented.

  For example, FIG. 7 is a graph showing an example of braking pressure increase suppression control at the start of the first braking after the traveling direction is reversed in the second embodiment.

  As shown in FIG. 7, after the vehicle has stopped braking, a shift operation for reversing the traveling direction is performed at time t1, and the braking operation by the driver is started at time t2, and the master cylinder pressure Pm is shown in FIG. Suppose that it is detected that the braking operation by the driver is started at time t3. In this case, the target braking pressure Pwti of each wheel gradually increases with an increasing gradient regulated by the correction coefficient Kb regardless of the increase in the master cylinder pressure Pm until the time t4 when the predetermined time Tb elapses from the time t3, and the time t4 Thereafter, the correction coefficient Kb is increased by an incremental amount ΔKb for each cycle until the provisional target braking pressure Pwtai becomes equal to or higher than the target braking pressure Pwti, whereby the corrected target braking pressure Pwti of each wheel is gradually increased to the target braking pressure before correction. You can get close to Pwti.

  In particular, according to the second embodiment shown in the drawing, in step 290, the correction coefficient Kb is variably set based on the vehicle speed V so as to increase as the vehicle speed V increases within a range greater than 0 and 1 or less. Since the pressure increase suppression time Tb is variably set based on the vehicle speed V so as to increase as the vehicle speed V decreases, the pressure increase suppression degree decreases so that the pressure increase suppression time decreases and the pressure increase suppression time increases as the vehicle speed V increases. And the pressure increase suppression time can be controlled, so that compared with the case where the pressure increase suppression degree or the pressure increase suppression time is constant, the driver's braking request due to the pressure increase suppression and the actual braking force It is possible to effectively prevent the generation of a cronk sound while reducing the divergence.

  Further, according to the illustrated embodiment 2, if the pressure increase suppression is continued for a predetermined time Tb or more, the correction coefficient Kb is increased by an increment amount ΔKb for each cycle. Therefore, when the predetermined time Tb elapses, the provisional target Before the braking pressure Pwtai becomes equal to or higher than the target braking pressure Pwti, for example, as compared with the case where the pressure increase suppression is continued with a constant correction coefficient larger than the correction coefficient Kb, the corrected target braking pressure Pwti is quickly corrected. The target braking pressure Pwti can be brought closer to the target braking pressure Pwti, and thereby the deviation between the driver's braking request and the actual braking force due to the suppression of the pressure increase can be quickly reduced.

  Further, according to the second embodiment shown in the figure, when a braking operation for sudden braking is performed by the driver, an affirmative determination is made in step 230, that is, braking is performed without executing steps 250 to 350. In step 360, the braking pressure Pwi of each wheel is controlled to become the corresponding target braking pressure Pwti without performing the pressure increase suppression control. Therefore, the driver performs a braking operation for sudden braking. In this case, it is possible to reliably prevent the driver's braking request for sudden braking due to suppression of pressure increase.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the brake pad 16 is pressed against the rotor disk 10 by the pressing force due to the pressure in the wheel cylinder 18, but the means for pressing the brake pad 16 is, for example, an electromagnetic In the above-described embodiments, the brake pad 16 is driven relative to the caliper 12 so that only the brake pad 16 is pressed against the rotor disk 10. It may be applied to the device.

  In the first embodiment, the transmission is an automatic transmission. However, the first embodiment may be applied to a vehicle in which the transmission is a manual transmission. Then, it is determined whether or not the clutch has been engaged by the driver. When a negative determination is made, the routine proceeds to step 130, and when an affirmative determination is made, the routine proceeds to step 90.

  In the first embodiment described above, it is determined in step 70 whether or not the wheel is rotating. In step 80, it is determined whether or not the braking operation by the driver is released. However, at least one of these steps may be omitted.

  In the above-described first embodiment, the predetermined pressurization time Ta is calculated according to the average value Vwa of the wheel speed so as to become shorter as the average value Vwa of the wheel speed becomes higher in step 90. However, the predetermined pressurization time Ta may be a predetermined time set in advance.

  Further, in the second embodiment, the increment ΔKb of the correction coefficient Kb is constant. For example, the target braking pressure Pwti of each wheel and the provisional target braking pressure Pwtai at the time when a predetermined time Tb has elapsed. It may be variably set so as to increase as the difference between and increases.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows Example 1 of the friction braking apparatus of the vehicle by this invention applied to the vehicle carrying an automatic transmission. 3 is a flowchart showing a braking force control routine in the first embodiment. 7 is a flowchart showing a braking force control routine in Embodiment 2. FIG. 3 is an explanatory diagram showing relative movement of the brake pad with respect to the caliper in the first embodiment. It is explanatory drawing which shows the relative movement of the brake pad with respect to the caliper in the conventional friction braking device. 5 is a graph showing an example of braking force control when the braking operation is released by the driver after the traveling direction of the vehicle is reversed in the first embodiment. 7 is a graph showing an example of braking pressure increase suppression control at the start of the first braking after the traveling direction is reversed in the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotor disk 12 Caliper 16 Brake pad 18 Wheel cylinder 24 Master cylinder 26 Electronic controller 28, 30i Pressure sensor 32 Shift position (SP) sensor 34i Wheel speed sensor

Claims (7)

Based on a rotating member that rotates together with the wheel, a friction material, a caliper that accommodates and supports the friction material with a predetermined clearance, a pressing means that presses the friction material against the rotating member, and at least based on a braking operation of the driver In the vehicle friction braking device having a control means for controlling the pressing of the pressing means, the control means has means for detecting the traveling direction of the vehicle, the traveling direction of the vehicle is reversed and the wheels start to rotate. that presses the friction member against the rotating member of the friction member in the rotational direction with minimal pressure sufficient to cause relative movement with respect to the caliper by the pre-serial pressing means of the rotary member when A vehicle friction braking device.   The vehicle is a vehicle equipped with an automatic transmission, and the control means starts pressing by the pressing means when the driver releases the braking operation after detecting the reverse operation of the traveling direction of the vehicle by the driver. The friction braking device for a vehicle according to claim 1, wherein:   The vehicle is a vehicle equipped with a manual transmission, and the control means starts pressing by the pressing means when a clutch is engaged by the driver after detecting a reverse operation of the traveling direction of the vehicle by the driver. The friction braking device for a vehicle according to claim 1, wherein:   The said control means has a means to detect rotation of a wheel, and when the rotation of the wheel to the direction where the advancing direction of a vehicle reverses is detected, the press by the said press means is started, The 1st characterized by the above-mentioned. 4. A friction braking device for a vehicle according to any one of claims 1 to 3.   5. The friction braking device for a vehicle according to claim 1, wherein the pressing by the pressing means is continued for a preset time.   6. The preset time is a time sufficient to move the friction material relative to the caliper in the rotation direction of the rotating member after the traveling direction of the vehicle is reversed. The vehicle friction braking device as described.   Based on a rotating member that rotates together with the wheel, a friction material, a caliper that accommodates and supports the friction material with a predetermined clearance, a pressing means that presses the friction material against the rotating member, and at least based on a braking operation of the driver In the vehicle friction braking device having a control means for controlling the pressing of the pressing means, the control means has a means for detecting the traveling direction of the vehicle, and the reverse of the traveling direction of the vehicle is detected. A vehicle friction braking device, wherein an increase gradient of a pressing force by the pressing means is made smaller than that at the time of starting braking when the reverse of the traveling direction of the vehicle is not detected at the time of initial braking.

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