JP4192840B2 - Disc brake device - Google Patents

Description

  The present invention relates to a disc brake device that improves braking feeling.

The disc brake device generates a braking force by sandwiching a disc rotor that rotates together with a wheel from left and right sides with brake pads, and bringing two brake pads into contact with the disc rotor by operation of a piston. Some disc brake devices have hysteresis in the braking force with respect to the operation amount of the brake pedal (see Patent Document 1).
JP 2001-206208 A

  However, in the conventional disc brake device, when the amount of operation of the brake pedal decreases compared to when the amount of operation of the brake pedal increases, a change in braking force increases with respect to the amount of operation of the brake pedal due to hysteresis. Therefore, when the driver returns the brake pedal or when the vehicle stops, the driver receives a strong feeling of deceleration, and the braking feeling deteriorates.

  Then, this invention makes it a subject to provide the disc brake device which can improve a braking feeling.

  A disc brake device according to the present invention includes a plurality of friction materials that are located on at least one surface side of a disc rotor and have different braking force changes with respect to a change in pressing force, and a plurality of friction material pressing means that press the plurality of friction materials. A caliper having a pressing force setting means for setting each pressing force to the plurality of friction materials so as to obtain a target braking force, and the pressing force setting means is used when the target braking force is decreased than when the target braking force is increased. Each pressing force is set so that the ratio of the braking force due to the friction material with a small change in the braking force relative to the change in the pressing force to the total braking force is larger than the braking force due to the friction material with a large change in the braking force with respect to the change in the pressing force. It is characterized by doing.

  In this disc brake device, a friction material sandwiched from both the left and right sides of the disc rotor is attached to the caliper, and a plurality of friction materials and a plurality of friction material pressing means are provided on at least one side of both sides. The plurality of friction materials have different characteristics, and the change in the braking force is different from the change in the pressing force. In other words, there are friction materials that have a large change in braking force for a given change in pressing force, and friction materials that have a small change in braking force. Gradually changes. In the disc brake device, when the target braking force is decreased by the pressing force setting means as compared with the case where the target braking force is increased, the braking force by the friction material having a smaller braking force change than the braking force by the friction material having the larger braking force change is set. Each pressing force is set to the plurality of friction materials so that the ratio of the power to the total braking force is increased. In the disc brake device, the pressing force set for each of the plurality of friction materials is output by the plurality of friction material pressing means, and the ratio of the braking force by the friction material with a small change in the braking force to the total braking force is increased. And press the disk rotor. As a result, when the driver reduces the braking force such as returning the brake pedal, the braking force that has been sharply reduced with respect to the decrease in the pressing force can be gradually reduced, thus improving the braking feeling. To do.

  The target braking force is a target braking force that is generated by the disc brake device. For example, a hydraulic pressure corresponding to a driver's operation amount with respect to the brake pedal, a brake such as ABS (Anti-Lock Brake System), etc. It is a braking force signal from the control device to control.

A disc brake device according to the present invention includes a plurality of friction materials that are located on at least one surface side of a disc rotor and have different braking force changes with respect to a change in pressing force, and a plurality of friction material pressing means that press the plurality of friction materials. And a pressing force setting means for setting each pressing force to the plurality of friction materials so as to achieve a target braking force. The pressing force setting means has a pressing force when the vehicle speed is lower than the first predetermined vehicle speed. Each pressing force is set so that the ratio of the braking force due to the friction material with a small change in the braking force relative to the change in the pressing force to the total braking force becomes larger than the braking force due to the friction material with a large change in the braking force relative to the change in Features.

  In this disc brake device, a friction material sandwiched from both the left and right sides of the disc rotor is attached to the caliper, and a plurality of friction materials and a plurality of friction material pressing means are provided on at least one side of both sides. In the disc brake device, when the vehicle speed is low as compared with the case where the vehicle speed is high, the disc brake device has a braking force by the friction material having a smaller change in the braking force than a braking force by the friction material having a large change in the braking force with respect to the total braking force. Each pressing force is set to a plurality of friction materials so that the ratio becomes large. In the disc brake device, the pressing force set for each of the plurality of friction materials is output by the plurality of friction material pressing means, and the ratio of the braking force by the friction material having a small change in the braking force to the total braking force is increased. And press the disk rotor. Thereby, when decelerating or stopping, the braking force that has been greatly changed by the change in the pressing force can be gradually changed, so that the braking feeling is improved.

In the above-described disc brake device of the present invention, when the target braking force is decreased from when it is increased or when the vehicle speed is lower than the second predetermined vehicle speed that is lower than the first predetermined vehicle speed , the change in the braking force with respect to the change in the pressing force. It is good also as a structure which does not use a friction material with large, but generates a braking force using a friction material with a small change of the braking force with respect to the change of pressing force.

  In this disc brake device, the pressing force setting means sets the pressing force of the friction material having a large change in the braking force to 0 when the target braking force is decreased or lower than when the vehicle speed is high. Only the pressing force of the friction material with a small change in braking force is set. In the disc brake device, the friction material pressing means outputs a pressing force set only to the friction material with a small change in braking force, and presses the disc rotor only with the friction material with a small change in braking force. As a result, the braking force can be gradually changed.

  According to the present invention, it is possible to improve the braking feeling by appropriately controlling a plurality of friction materials having different braking force changes with respect to the pressing force.

  Embodiments of a disc brake device according to the present invention will be described below with reference to the drawings.

  In the present embodiment, the disc brake device according to the present invention is applied to a disc brake device mounted on an automobile. The disc brake device according to the present embodiment includes two calipers having different control performance and nine pistons in each caliper, and in order to set each friction material to an individual pressing force, a target axial force is applied to each piston. Set (target piston displacement). In particular, in the disc brake device according to the present embodiment, the target axial force of each piston is set for the purpose of improving the braking feeling. In particular, the disc brake device according to the present embodiment improves the braking feeling when the brake is released and when the vehicle is stopped.

  With reference to FIGS. 1-3, the whole structure of the disc brake apparatus 1 is demonstrated. FIG. 1 is a configuration diagram of a control portion of the disc brake device according to the present embodiment. FIG. 2 is a diagram showing an example of the configuration of the piston and brake pad of the disc brake device according to the present embodiment, where (a) is a side view and (b) is a front view. FIG. 3 is a diagram showing another example of the configuration of the piston and brake pad of the disc brake device according to the present embodiment, in which (a) is a side view and (b) is a front view.

  The disc brake device 1 is a device that generates a braking force in response to an operation on a brake pedal by a driver. The disc brake device 1 uses two friction materials having different control performances in order to improve the braking feeling. Therefore, in the disc brake device 1, in order to press the two friction materials uniformly, each caliper is provided with nine pistons, and the nine pistons are individually controlled. For this purpose, the disc brake device 1 mainly includes a disc rotor (not shown), a caliper 2, a brake performance control device 3, a vehicle speed sensor 4, a brake sensor 5, and first to ninth axial force sensors 6a to 6i. The first to ninth displacement sensors 7a to 7i are provided. In the present embodiment, the brake performance control device 3 corresponds to the pressing force setting means described in the claims.

  The disc brake device 1 is provided with a disc rotor in parallel with each wheel, and a caliper 2 is provided for each disc rotor. The caliper 2 is provided with brake pads 20 on both sides of the disk rotor. Nine pistons 22a to 22i are provided on the side opposite to the disk rotor side of the brake pad 20 on the inner side of the vehicle. Further, the caliper 2 is provided with first to ninth actuators 23a to 23i for operating the first to ninth pistons 22a to 22i in response to the first to ninth control signals from the brake performance control device 3. It has been. In the caliper 2, the inner brake pad 20 is pressed by the pistons 22a to 22i, and the disc rotor is pressed by the inner brake pad 20. Further, the caliper 2 receives the reaction force from the disk rotor and moves to the inner side, and presses the disk rotor also by the brake pad 20 on the outer side. Thus, the disc brake device 1 generates a braking force. In particular, in the disc brake device 1, the braking force has hysteresis with respect to the operation amount of the brake pedal.

  The brake pad 20 includes a first friction material 20a, a second friction material 20b, and a back metal 20c. The friction materials 20a and 20b are disposed on the disk rotor side, and the back metal 20c is attached to the back surfaces of the friction materials 20a and 20b. . The first friction material 20a is a friction material having a high friction coefficient. The second friction material 20b is a friction material having a lower coefficient of friction than the first friction material 20a. Further, the second friction material 20b is a friction material having a better control performance than the first friction material 20a, in which the change in the braking force and the friction coefficient is smaller with respect to the change in the total axial force of the piston. In addition to the total axial force of the piston, the friction material having good control performance may be a friction material whose change is small with respect to the vehicle speed and the temperature of the friction material.

  Examples of the arrangement and shape of the first friction material 20a and the second friction material 20b include a pattern as shown in FIG. 2 and a pattern as shown in FIG. In the pattern shown in FIG. 2, the first friction material 20a and the second friction material 20b have a rectangular shape that is long along the rotation direction of the disk rotor, and the length of the disk rotor in the rotation direction is the same. The radial length is different. The first friction material 20a is disposed on the outer peripheral side of the disk rotor, and the length of the disk rotor in the radial direction is approximately one third of the entire friction material. The second friction material 20b is disposed on the inner peripheral side of the disk rotor, and the length of the disk rotor in the radial direction is approximately two-thirds of the entire friction material. In the pattern shown in FIG. 3, the first friction material 20a and the second friction material 20b have a rectangular shape that is long along the radial direction of the disk rotor and have the same size. Only one first friction material 20a is disposed at the center in the rotational direction of the disk rotor. One second friction material 20b is arranged on each of the inlet side and the outlet side in the rotational direction of the disk rotor. In the following description, the arrangement and shape of the pattern shown in FIG.

  The pistons 22a to 22i are slidably provided in nine cylinder bores (not shown) provided in the caliper 2, respectively. The pistons 22a to 22i are arranged in three rows along the rotation direction of the disk rotor and are arranged in three rows along the radial direction. The first to third pistons 22a to 22c are arranged on the outlet side in the rotation direction of the disk rotor, and are arranged in order of the first piston 22a, the second piston 22b, and the third piston 22c from the inner peripheral side of the disk rotor. . The fourth to sixth pistons 22d to 22f are arranged at the center in the rotation direction of the disk rotor, and are arranged in order of the fourth piston 22d, the fifth piston 22e, and the sixth piston 22f from the inner peripheral side of the disk rotor. The seventh to ninth pistons 22g to 22i are arranged on the inlet side in the rotation direction of the disk rotor, and are arranged in order of the seventh piston 22g, the eighth piston 22h, and the ninth piston 22i from the inner peripheral side of the disk rotor. . Accordingly, the first friction material 20a is pressed by the third piston 22c, the sixth piston 22f, and the ninth piston 22i, and the second friction material 20b is the first piston 22a, the second piston 22b, the fourth piston 22d, and the fifth piston. 22e, the seventh piston 22g, and the eighth piston 22h (see FIG. 2B).

  Axial force sensors 6a to 6i and displacement sensors 7a to 7i are attached to the pistons 22a to 22i, respectively. Each of the axial force sensors 6a to 6i detects the axial force of each of the pistons 22a to 22i, and transmits the detected value to each of the actuators 23a to 23i as first to ninth axial force signals, and the brake performance control device 3 Also send to. The displacement sensors 7a to 7i detect the displacement amounts of the pistons 22a to 22i, respectively, and transmit the detected values to the actuators 23a to 23i as first to ninth displacement signals, respectively, and also to the brake performance control device 3. Send.

  The vehicle speed sensor 4 is attached to each wheel. The vehicle speed sensor 4 detects the rotational speed of the wheel and transmits the detected value to the brake performance control device 3 as a vehicle speed signal. Although the vehicle speed is calculated based on the rotational speed of each wheel in the brake performance control device 3, other vehicle speed sensors other than the vehicle speed sensor 4 may be used. The brake sensor 5 is attached to the brake pedal. The brake sensor 5 detects the amount of operation of the brake pedal, and transmits the detected value to the brake performance control device 3 as a brake signal.

  The brake performance control device 3 will be described with reference to FIGS. 1, 2, 4, and 5. FIG. 4 is a diagram showing the relationship between the brake pedal operation amount and the braking force when the brake releasing process is performed in the effectiveness stabilizing portion of FIG. FIG. 5 is a diagram showing the relationship between the braking time and the vehicle speed when the smart stop process is performed in the effect stabilizing portion of FIG.

  The brake performance control device 3 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like. In the brake performance control device 3, detection signals are taken from the various sensors 4, 5, 6 a to 6 i, 7 a to 7 i, and the first friction material 20 a and the second friction material 20 b (as a result, the first to the first) are based on the various detection signals. The target axial force for each of the 9 pistons 22a to 22i) is set, and the friction materials 20a and 20b are independently controlled by the first to ninth pistons 22a to 22i of the caliper 2 provided on each wheel. Incidentally, the target axial force of the first friction material 20a is the sum of the target axial forces of the third piston 22c, the sixth piston 22f, and the ninth piston 22i, and the target axial force of the second friction material 20b is the first piston. The target axial force of 22a, 2nd piston 22b, 4th piston 22d, 5th piston 22e, 7th piston 22g, and 8th piston 22h is united. In particular, in the brake performance control device 3, a control amount for improving the braking feeling is added to the target axial force (target piston displacement). For this purpose, the brake performance control device 3 includes a reference target axial force calculation unit 30, a target axial force calculation unit 31, a target piston displacement calculation unit 32, and an effect stabilization unit 33.

  The reference target axial force calculation unit 30 takes in the control oil pressure corresponding to the operation amount of the brake pedal of the driver, and calculates the reference target axial force of each piston 22a to 22i based on this control oil pressure. In particular, in the reference target axial force calculation unit 30, in order to give hysteresis to the change in the braking force with respect to the operation amount of the brake pedal, when the operation amount of the brake pedal decreases than when the operation amount of the brake pedal increases. The reference target axial force is calculated so that the change of the braking force becomes larger with respect to the operation amount of the brake pedal (when the brake is released). The change in the braking force with respect to the brake pedal operation amount indicated by the broken line in FIG. 4 is a change when the pistons 22a to 22i are operated by the reference target axial force, and has hysteresis. The reference target axial force is set to the same value for the nine pistons 22a to 22i.

In the target axial force calculation unit 31, the target axial force change amount of the piston that changes the target axial force with respect to the reference target axial force is taken in from the effect stabilizing unit 33. The effectiveness stabilizing unit 33 sets the target axial force change amount so as to satisfy the condition of the following expression (1). In the target axial force calculation unit 31, for each piston 22a to 22i, the target axial force is calculated by adding the target axial force change amount to the reference target axial force for the piston for which the target axial force change amount is set. For the piston whose target axial force change amount is 0, the reference target axial force is used as the target axial force as it is. The target axial force is set to an individual value for each of the nine pistons 22a to 22i for each wheel. Therefore, 36 values are set as the target axial force.

  μi is a friction coefficient of the first friction material 20a or the second friction material 20b. Fi is the axial force of each piston 22a-22i. Ri is the length (radius) from the center of the disk rotor to the center of each piston.

  The target piston displacement calculation unit 32 calculates the target piston displacement based on the target axial force calculated by the target axial force calculation unit 31 for each of the pistons 22a to 22i. And the target piston displacement calculation part 32 transmits the target piston displacement of each piston 22a-22i to each actuator 23a-23i as a 1st-9th control signal for every wheel, respectively. The piston displacement is set to 36 values corresponding to the target axial force.

  The effectiveness stabilizing portion 33 changes the total axial force applied to the friction materials 20a and 20b in order to improve the braking feeling when the brake is released and when the vehicle is stopped. For this purpose, the effectiveness stabilizing unit 33 performs a brake release process and a smart stop process, and sets a target axial force change amount of each of the pistons 22a to 22i. In the brake release process, when the driver returns the brake pedal (that is, when the braking force is reduced), a target axial force change amount for using only the second friction material 20b for a certain period is set. In the smart stop process, when the vehicle is decelerating to stop, a target axial force change amount for increasing the usage rate of the second friction material 20b is set step by step.

  The brake release process will be described. The effect stabilizing unit 33 takes in the operation amount of the brake pedal by the brake signal from the brake sensor 5. The effect stabilizing unit 33 calculates a change in the operation amount of the brake pedal per unit time, and uses the calculated value as the operation change amount. Regarding the operation change amount, the change amount when the operation amount of the brake pedal is increased is a positive value, and the change amount when the operation amount of the brake pedal is decreasing is a negative value.

  The effectiveness stabilizing unit 33 determines whether or not the operation change amount becomes smaller than 0 after the brake is turned on. When the operation change amount becomes smaller than 0, the effectiveness determination unit 33 determines whether or not the predetermined time α has elapsed. The fixed time α is set in consideration of the friction coefficient characteristics of the second friction material 20b and the like, and is a sufficient time for improving the braking feeling by using only the second friction material 20b. The period for using only the second friction material 20b is defined by whether or not the fixed time α has elapsed. However, the amount of reduction in axial force or the amount of braking force when only the second friction material 20b is used, etc. It may be defined by whether or not a certain amount has been reached.

  While the fixed time α elapses, the effectiveness determination unit 33 sets a target axial force change amount of the first friction material 20a for setting the axial force of the first friction material 20a to zero. Further, the effectiveness stabilizing unit 33 sets the target axial force change amount of the second friction material 20b so that the axial force is increased by reducing the axial force on the first friction material 20a so as to satisfy the condition of the expression (1). calculate. That is, the target axial force change amount of each friction material 20a, 20b for using only the second friction material 20b is calculated. When the fixed time α elapses, the effectiveness stabilizing unit 33 sets the target axial force change amount of each of the friction materials 20a and 20b to 0 in order to return the first friction material 20a and the second friction material 20b to the reference target axial force. To do.

  When the effectiveness stabilizing portion 33 calculates the target axial force change amount of each friction material 20a, 20b, the target of the third piston 22c, the sixth piston 22f, and the ninth piston 22i is calculated from the target axial force change amount with respect to the first friction material 20a. An axial force change amount is set, and the first piston 22a, the second piston 22b, the fourth piston 22d, the fifth piston 22e, the seventh piston 22g, and the eighth piston 22h are determined from the target axial force change amount with respect to the second friction material 20b. Set the target axial force change amount. The effectiveness stabilizing unit 33 outputs the target axial force change amount of each of the pistons 22 a to 22 i to the target axial force calculating unit 31.

  Thus, by performing the brake releasing process in the stabilizing part 33, when the operation amount of the brake pedal is shifted from the increasing state to the decreasing state, the braking force is increased using only the second friction material 20b. generate. Since the second friction material 20b has good control performance, the braking force changes only gradually even if the total axial force on the second friction material 20b changes. Therefore, when the brake is released, the braking force gradually decreases as shown by the solid line in FIG. Incidentally, when the first friction material 20a having inferior control performance is also used, as shown by the broken line in FIG.

  The smart stop process will be described. The effect stabilizing unit 33 takes in the vehicle speed based on the vehicle speed signal from the vehicle speed sensor 4. The effectiveness stabilizing unit 33 determines whether or not the vehicle speed has become lower than the first vehicle speed V1 after the brake is turned on (see FIG. 5). The first vehicle speed V1 is a low vehicle speed. When the vehicle speed becomes lower than the first vehicle speed V1, the effectiveness stabilizing unit 33 sets the target axial force change amount of the first friction material 20a so that the axial force of the first friction material 20a decreases to zero. At this time, the method of decreasing the axial force of the first friction material 20a may be decreased linearly or decreased nonlinearly. Further, the effectiveness stabilizing unit 33 sets the target axial force change amount of the second friction material 20b so that the axial force is increased by reducing the axial force on the first friction material 20a so as to satisfy the condition of the expression (1). calculate. That is, in order to gradually stop using the first friction material 20a, the target axial force change amount of each friction material 20a, 20b is calculated.

  After the vehicle speed becomes lower than the first vehicle speed V1, the effect stabilizing unit 33 determines whether or not the vehicle speed becomes lower than the second vehicle speed V2 (see FIG. 5). The second vehicle speed V2 is lower than the first vehicle speed V1. When the vehicle speed becomes lower than the second vehicle speed V2, the effect stabilizing unit 33 sets a target axial force change amount of the first friction material 20a for setting the axial force of the first friction material 20a to zero. Further, the effectiveness stabilizing unit 33 sets the target axial force change amount of the second friction material 20b so that the axial force is increased by reducing the axial force on the first friction material 20a so as to satisfy the condition of the expression (1). calculate.

  In the effect stabilizing unit 33, similarly to the above, the target axial force change amount of each piston 22a to 22i is set from the target axial force change amount of each friction material 20a, 20b, and the target axial force change amount of each piston 22a to 22i. Is output to the target axial force calculation unit 31.

  By performing the smart stop process in the effect stabilizing unit 33 in this way, when the vehicle becomes a low vehicle speed, the usage rate of the second friction material 20a is gradually increased to generate a braking force. A braking force is generated using only the friction material 20b. Even if the total axial force on the second friction material 20b is changed, the change in braking force is small, so the braking force changes gradually and the vehicle speed also changes gradually. Therefore, when the vehicle stops, as shown by the solid line in FIG. 5, the braking time becomes slightly longer, but the vehicle speed gradually decreases.

  The operation of the disc brake device 1 will be described with reference to FIG. In particular, the brake release process in the effectiveness stabilizing unit 33 will be described with reference to the flowchart of FIG. 6, and the smart stop process will be described with reference to the flowchart of FIG. FIG. 6 is a flowchart showing a flow of brake release processing in the effect stabilizing portion of FIG. FIG. 7 is a flowchart showing the flow of smart stop processing in the effect stabilizing unit of FIG.

  When the driver operates the brake pedal, in the disc brake device 1, the control hydraulic pressure corresponding to the operation amount is input to the brake performance control device 3. The brake performance control device 3 calculates a reference target axial force based on the control hydraulic pressure. Further, in the brake performance control device 3, for each wheel, the target axial force change amount of each piston 22a to 22i by the effectiveness stabilizing unit 33 is added to the reference target axial force, and the target axial force of each piston 22a to 22i is respectively determined. calculate. And in the brake performance control apparatus 3, the target piston displacement of each piston 22a-22i is each calculated from the target axial force of each piston 22a-22i for every wheel, and each target piston displacement is 1st-9th control signal. Is transmitted to each of the actuators 23a to 23i.

  When each control signal is received, the actuators 23a to 23i hydraulically control the operations of the pistons 22a to 22i so as to achieve the target piston displacements. At this time, the actuators 23a to 23i perform feedback control so as to achieve the respective target piston displacements based on the axial force signals from the axial force sensors 6a to 6i and the displacement signals of the displacement sensors 7a to 7i. Then, the pistons 22a to 22i are displaced so as to be the respective target piston displacements, and the first friction material 20a and the second friction material 20b in the brake pad 20 on the inner side are pressed by individually set axial forces. . Eventually, the first friction material 20a and the second friction material 20b of the inner brake pad 20 come into contact with the disk rotor, and the brake pad 20 presses the disk rotor. Further, in the disc brake device 1, the caliper 2 receives the reaction force from the disc rotor and moves to the inner side, and also presses the disc rotor with the brake pad on the outer side of the caliper 2 to generate a braking force.

  At this time, when the effectiveness stabilizing unit 33 determines that the brake is turned on based on the control hydraulic pressure (S10), the operation amount of the brake pedal is acquired from the brake signal from the brake sensor 5 (S11). The effectiveness stabilizing unit 33 calculates an operation change amount per unit time based on the acquired operation amount of the brake pedal (S12).

  The effectiveness stabilizing unit 33 determines whether or not the operation change amount is smaller than 0, and if it is equal to or larger than 0, the process returns to the process of S11 (S13). When the operation change amount becomes smaller than 0, the effect stabilizing unit 33 determines whether or not a predetermined time α has elapsed since the operation change amount became smaller than 0 (S14). While the fixed time α does not elapse, the effectiveness stabilizing unit 33 calculates the target axial force change amount of each friction material 20a, 20b in order to use only the second friction material 20b (S15). When the fixed time α elapses, the effect stabilizing unit 33 sets the target axial force change amount of each friction material 20a, 20b to 0 in order to obtain a normal use state by the first friction material 20a and the second friction material 20b. (S16).

  Further, the effectiveness stabilizing unit 33 calculates whether the target axial force change amount of each piston 22a to 22i is calculated from the target axial force change amount of each friction material 20a, 20b, and then whether or not the brake is turned off based on the control hydraulic pressure. Is determined (S17). The effectiveness stabilizing unit 33 repeatedly executes the processes of S11 to S16 until the brake is turned off, and ends the process when the brake is turned off.

  When the driver starts to return the brake pedal (when releasing the brake is started), the brake performance control device 3 uses a target axial force change amount of each of the pistons 22a to 22i set by the effectiveness stabilizing unit 33 for a certain time α. The target axial force for the first friction material 20a is set to 0, and the target axial force for the second friction material 20b is increased accordingly. As a result, the braking force is generated only by the second friction material 20b, and the braking force gradually decreases as compared with the case where the first friction material 20a is also used.

  Further, when the effectiveness stabilizing unit 33 determines that the brake is turned on based on the control oil pressure (S20), the vehicle speed is acquired based on the vehicle speed signal from the vehicle speed sensor 4 (S21).

  The effectiveness stabilizing unit 33 determines whether or not the vehicle speed is lower than the first vehicle speed V1. If the vehicle speed is equal to or higher than the first vehicle speed V1, the process proceeds to S26 (S22). When the vehicle speed becomes lower than the first vehicle speed V1, the effectiveness stabilizing unit 33 determines whether or not the vehicle speed is lower than the second vehicle speed V2 (S23). When the vehicle speed is equal to or higher than the second vehicle speed V2 and lower than the first vehicle speed V1, the effectiveness stabilizing unit 33 gradually reduces the target axial force of the first friction material 20a to 0 and uses the reduced amount as the second friction material 20b. The target axial force change amount of each of the friction materials 20a and 20b is calculated so as to increase with the target axial force, and the process proceeds to S26 (S24). When the vehicle speed becomes lower than the second vehicle speed V2, the effectiveness stabilizing unit 33 calculates the target axial force change amount of each friction material 20a, 20b in order to use only the second friction material 20b, and proceeds to the processing of S26. (S25).

  Further, the effectiveness stabilizing unit 33 calculates whether the target axial force change amount of each piston 22a to 22i is calculated from the target axial force change amount of each friction material 20a, 20b, and then whether or not the brake is turned off based on the control hydraulic pressure. Is determined (S26). The effectiveness stabilizing unit 33 repeatedly executes the processes of S21 to S25 until the brake is turned off, and ends the process when the brake is turned off.

  When the vehicle decelerates to a low vehicle speed, the brake performance control device 3 gradually decreases the target axial force on the first friction material 20a to 0 by the amount of change in the target axial force of each piston 22a to 22i set by the effectiveness stabilizing unit 33. And the target axial force for the second friction material 20b is increased accordingly. Until the brake performance control device 3 further decelerates and stops, the target axial force on the first friction material 20a is set to 0 based on the target axial force change amount of each piston 22a to 22i set by the effectiveness stabilizing unit 33, and the second The target axial force for the friction material 20b is increased accordingly. Thereby, a braking force is generated by the first friction material 20a in which the ratio to the total braking force decreases and the second friction material 20b in which the ratio to the total braking force increases, and finally the braking force is generated only by the second friction material 20b. As a result, the braking force is gradually reduced and the vehicle speed is gradually reduced as compared with the case where the first friction material 20a and the second friction material 20b are used with the reference target axial force.

  According to this disc brake device 1, the axial force can be set independently for the two friction materials 20a and 20b having different control performances, and the friction materials 20a and 20b (each piston 22a to 22i) can be set. Axial force can be changed individually. Thereby, in the disc brake device 1, when the driver starts to return the brake pedal, the braking force is generated only by the second friction material 20b, so that the braking force gradually decreases with respect to the decrease in the operation amount of the brake pedal. A slow deceleration. In the disc brake device 1, when the vehicle stops, the braking force is generated while gradually increasing the usage rate of the second friction material 20b, so that the vehicle speed is gradually reduced and the vehicle is smoothly stopped. Can do. Therefore, for the driver, the braking feeling is improved and the brake operability is also improved.

  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 this embodiment, the disc brake device is applied to an automobile, but the present invention can also be applied to other devices equipped with a disc brake device such as an automobile motorcycle.

  Further, in this embodiment, only the piston that presses the brake pad on the one surface side of the disk rotor is provided, but the configuration that includes the piston that presses the brake pad on the one surface side of the disc rotor and the brake pad on the other surface side, respectively. It is good.

  Further, in the present embodiment, the first friction material and the second friction material having different friction coefficients are provided. However, friction materials having different characteristics may be used, or the number of friction materials, the arrangement, The shape and the like may be appropriately configured. In particular, in the present embodiment, the second friction material having a low friction coefficient is a friction material having a good control performance, but the friction material having a high friction coefficient may be a friction material having a good control performance. In some cases, the friction material is a friction material with good control performance.

  Further, in this embodiment, the configuration is provided with nine 3 × 3 pistons for one brake pad, but the shape and size of the brake pad, the piston radius, the number of friction materials, the arrangement, the shape, and the like are taken into consideration. Then, the number and arrangement of the pistons may be set as appropriate.

  In this embodiment, the driver's brake pedal operation amount (control hydraulic pressure) is used as the target braking force, but the vehicle is equipped with a system for controlling brakes such as ABS and inter-vehicle distance control on the vehicle side. Alternatively, the control signal from the system may be the target braking force.

  In this embodiment, the brake release process determines whether to release the brake based on the brake pedal operation amount. However, the brake pedal depression force, the control hydraulic pressure according to the brake pedal operation amount, etc. You may judge by thing.

It is a block diagram of the control part of the disc brake device which concerns on this Embodiment. It is a figure which shows an example of a structure of the piston and brake pad of the disc brake apparatus which concerns on this Embodiment, (a) is a side view, (b) is a front view. It is a figure which shows the other example of a structure of the piston and brake pad of the disc brake apparatus which concerns on this Embodiment, (a) is a side view, (b) is a front view. It is a figure which shows the relationship between the brake-pedal operating amount and braking force at the time of performing the brake releasing process in the effect stable part of FIG. It is a figure which shows the relationship between the braking time at the time of performing the smart stop process in the effect stable part of FIG. 1, and a vehicle speed. It is a flowchart which shows the flow of the brake removal process in the effectiveness stabilization part of FIG. It is a flowchart which shows the flow of the smart stop process in the effect stabilization part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Disc brake device, 2 ... Caliper, 3 ... Brake performance control device, 4 ... Vehicle speed sensor, 5 ... Brake sensor, 6a-6i ... 1st-9th axial force sensor, 7a-7i ... 1st-9th displacement Sensor, 20 ... Brake pad, 20a ... First friction material, 20b ... Second friction material, 20c ... Back metal, 22a-22i ... First to ninth pistons, 23a-23i ... First to ninth actuators, 30 ... Reference Target axial force calculation unit 31 ... Target axial force calculation unit 32 ... Target piston displacement calculation unit 33 ... Effective stabilization unit

Claims (3)

A caliper that is located on at least one surface side of the disk rotor and has a plurality of friction materials with different changes in braking force with respect to a change in pressing force and a plurality of friction material pressing means that press the plurality of friction materials;
Pressing force setting means for setting each pressing force on the plurality of friction materials so as to achieve a target braking force,
In the pressing force setting means, when the target braking force is decreased than when the braking force is increased, the change in the braking force with respect to the change in the pressing force is smaller than the braking force with the friction material having a large change in the braking force with respect to the change in the pressing force. A disc brake device characterized in that each pressing force is set so that a ratio of a braking force by a friction material to a total braking force is increased. A caliper that is located on at least one surface side of the disk rotor and has a plurality of friction materials with different changes in braking force with respect to a change in pressing force and a plurality of friction material pressing means that press the plurality of friction materials;
Pressing force setting means for setting each pressing force on the plurality of friction materials so as to achieve a target braking force,
When the vehicle speed is lower than the first predetermined vehicle speed , the pressing force setting means uses a friction material that has a smaller change in braking force with respect to a change in pressing force than a braking force with a friction material that has a large change in braking force with respect to a change in pressing force. A disc brake device, wherein each pressing force is set so that a ratio of a braking force to a total braking force is increased. When the target braking force is decreased from when it is increased or when the vehicle speed is lower than a second predetermined vehicle speed that is lower than the first predetermined vehicle speed, a friction material that has a large change in braking force with respect to a change in pressing force is not used. 3. The disc brake device according to claim 1, wherein the braking force is generated by using a friction material having a small change in the braking force with respect to the change in the pressing force.

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