JP4329613B2 - Disc brake device - Google Patents

Description

  The present invention relates to a disc brake device that presses a friction material by a plurality of friction material pressing means.

A disc brake device sandwiches a disc rotor that rotates with a wheel from both left and right sides with brake pads, and makes two braking pads (friction materials) contact the disc rotor by the operation of a piston (friction material pressing means). generate. In the disc brake device, a large braking force can be generated by increasing the brake pad. When the brake pad is enlarged, if the brake pad is pressed with one piston, the entire brake pad cannot be pressed uniformly. For this reason, some disc brake devices include a plurality of pistons in order to press a large brake pad uniformly. In a disc brake device having a plurality of pistons, for example, a spring member is provided on at least one of the plurality of pistons to delay the operation and not to operate simultaneously with other pistons, thereby preventing brake noise. There is a thing (refer patent document 1).
Japanese Utility Model Publication No. 4-44525

  However, in the conventional disc brake device, since a plurality of pistons are uniformly controlled, all the axial forces of the plurality of pistons are the same axial force. Therefore, in the conventional disc brake device, the contact state between the brake pad and the disc rotor cannot be changed even though there are a plurality of pistons. For this reason, even when a brake squeal occurs, the vibration state where the brake squeal cannot occur cannot be changed, and the brake squeal cannot be reduced. Thus, in the conventional disc brake device, since a plurality of pistons cannot be individually controlled, it is not possible to improve the brake performance such as brake noise.

  Then, this invention makes it a subject to provide the disc brake device which can perform appropriate control with respect to several friction material pressing means.

A disc brake device according to the present invention includes a caliper having a plurality of friction material pressing means located at least on one side of a disc rotor and disposed at different positions with respect to the friction material surface, and a reference target shaft based on control hydraulic pressure A pressing force for individually setting the pressing force of the plurality of friction material pressing means in consideration of a target axial force change amount calculated for at least one of squeal reduction, effectiveness stabilization and wear suppression with respect to force. It is characterized by comprising pressure setting means and pressing force output means for outputting each pressing force set by the pressing force setting means to each of the plurality of friction material pressing means.

  In this disc brake device, two friction materials sandwiched from the left and right sides of the disc rotor are attached to the caliper, and at least one side of the friction materials on both sides is pressed by a plurality of friction material pressing means. In the disc brake device, the pressing force is set for each friction material pressing means based on the target braking force by the pressing force setting means, and the pressing force set individually by the pressing force output means is applied to each friction material pressing means, respectively. Output. Thus, in the disc brake device, the plurality of friction material pressing means can be controlled independently, and each portion of the friction material disposed on each friction material pressing means can be pressed with different pressing forces. Therefore, the pressure distribution on the friction material surface can be changed, and the contact state between the friction material and the disk rotor can be changed. Thus, in the disc brake device, appropriate control can be performed on the plurality of friction material pressing means, and various controls for improving the brake performance can be performed by changing the pressing force of each piston.

  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 an ABS (Anti-Lock Brake System), or the like is applied to the vehicle. It is a braking force signal from the control device to control.

  In the disc brake device of the present invention, the pressing force setting means arbitrarily selects a friction material pressing means that is different every predetermined time, and the selected friction material pressing means has a size different from that of the other friction material pressing means. It is good also as a structure which sets the pressing force of.

  In this disc brake device, a different friction material pressing means is arbitrarily selected from a plurality of friction material pressing means at a predetermined time by the pressing force setting means, and another friction material pressing means is pressed against the selected friction material pressing means. A pressing force having a magnitude different from that of the means is set. In the disc brake device, the pressing force output means causes the selected friction material pressing means to output a pressing force different from that of the other friction material pressing means. Therefore, the pressure distribution on the friction material surface changes every predetermined time, and the contact state between the friction material and the disk rotor changes. As a result, the vibration state due to the friction between the friction material and the disc rotor changes every predetermined time, so that the sound having the same vibration characteristics (brake squeal) does not continuously occur, and the brake squeal can be prevented from continuing. . As described above, in the disc brake device, brake squeal can be reduced by pressing an arbitrary portion of the friction material with a pressing force different from other portions every predetermined time.

  It should be noted that the predetermined time is a short time that does not matter to the person even when a sound is generated due to the same vibration state (brake squeal generation condition), and is a fixed time.

  In the disk brake device of the present invention, the pressing force setting means selects a friction material pressing means having a different radial position of the disk rotor every predetermined time, and another friction material pressing means is selected as the selected friction material pressing means. It is good also as a structure which sets the pressing force of a magnitude | size different from a means.

  In this disk brake device, the friction material pressing means having a different radial position of the disk rotor is selected every predetermined time by the pressing force setting means, and another friction material pressing means is selected with respect to the selected friction material pressing means. Set a different pressing force. In the disc brake device, the pressing force output means causes the selected friction material pressing means to output a pressing force different from that of the other friction material pressing means. For this reason, the pressure distribution in the radial direction of the disk rotor on the friction material surface changes every predetermined time, and the angle of the disk rotor surface with respect to the friction material surface in the axial direction of the disk rotor changes. As a result, the vibration state of the disk rotor in the axial direction changes every predetermined time, and the sound having the same vibration characteristics (brake squeal) is not continuously generated, so that the brake squeal can be prevented from continuing. In this case, in the disc brake device, the vibration state can be changed most efficiently by changing the pressing force of the friction material pressing means along the radial direction of the disc rotor every predetermined time, and the brake squeal can be efficiently performed. Can be reduced.

  In the above-described disc brake device of the present invention, the pressing force setting means has a pressing force having a magnitude different from that of the other friction material pressing means at any friction material pressing means among the plurality of friction material pressing means at any time. It is good also as a structure which sets.

  In this disc brake device, the pressing force setting means sets a pressing force having a magnitude different from that of the other friction material pressing means to any friction material pressing means of the plurality of friction material pressing means at any time. The pressing force output means causes the friction material pressing means to output a pressing force different from that of the other friction material pressing means. Therefore, the pressure distribution on the friction material surface changes every arbitrary time, and the vibration state due to the friction between the friction material and the disk rotor changes. That is, it is possible to prevent a sound with different vibration characteristics (brake squeal) from being generated at random time intervals and the brake squeal to be sustained. Thus, in the disc brake device, brake squeal can be reduced by pressing an arbitrary portion of the friction material at a random time interval with a pressing force different from other portions.

  It should be noted that the arbitrary time is a short time interval that is so short that a person does not care about the sound when the sound is generated at different time intervals due to different vibration states, and is a random time.

  In the above-described disc brake device of the present invention, the pressing force setting means selects two friction material pressing means among the plurality of friction material pressing means, and does not select one of the selected friction material pressing means. It is preferable to set the pressing force increased by the friction material pressing means, and to set the pressing force by reducing the increased pressing force to the other selected friction material pressing means.

  In this disk brake device, the pressing force setting means selects two friction material pressing means, and the pressing force is increased with respect to the selected one friction material pressing means compared to the other friction material pressing means not selected. And a pressing force that reduces the increase of the other friction material pressing means is set. In the disc brake device, the pressing force output means causes only the selected two friction material pressing means to output a pressing force different from that of the other friction material pressing means, and the total pressing force of all the friction material pressing means is as follows. Do not change. Therefore, the vibration state of the disk rotor is changed by the two selected friction material pressing means, and the target braking force required for the entire disk brake device can be output.

  In the disc brake device of the present invention, the pressing force setting means has a larger pressing force than the friction material pressing means arranged on the inner peripheral side in the friction material pressing means arranged on the outer peripheral side with respect to the radial direction of the disk rotor. It is good also as a structure which sets.

  In this disc brake device, the pressing force setting means causes the friction material pressing means disposed on the radially outer peripheral side of the disk rotor from the plurality of friction material pressing means to have a larger pressing force than the friction material pressing means disposed on the inner side. Is set, and the pressing force output means causes the outer peripheral friction material pressing means to output a larger pressing force than the inner peripheral friction material pressing means. The greater the distance from the center of rotation of the disc rotor to the position where the braking force is generated, the greater the braking force torque generated with the same amount of pressing force. A large braking torque can be obtained as compared with the case where the pressing force of the circumferential friction material pressing means is increased. Therefore, when a predetermined braking torque is generated, the energy consumption for outputting the friction material pressing means is reduced when the outer friction material pressing means outputs a larger pressing force than the inner friction material pressing means. it can. That is, the energy efficiency for generating the same braking torque is increased. For example, in order not to change the feeling of deceleration received by the driver even when the vehicle weight increases due to an increase in the load, etc., the same braking torque is applied to the same brake pedal operation amount as when the vehicle weight does not increase. Need to be generated. In this case, in this disc brake device, even if the vehicle weight increases, energy consumption is increased so much by causing the outer friction material pressing means to output a larger pressing force than the inner friction material pressing means. The same braking torque can be generated.

  In the above-described disc brake device of the present invention, the pressing force setting means is arranged on the outer peripheral side with respect to the radial direction of the disc rotor when the friction coefficient of the friction material decreases below the reference value or when the vehicle weight increases above the reference value. It is preferable to set a larger pressing force to the friction material pressing means arranged on the inner side than the friction material pressing means arranged on the inner peripheral side.

  When the friction coefficient of the friction material decreases below the reference value or when the vehicle weight increases above the reference value, if the normal pressing force is output to each of the friction material pressing means, the braking force decreases from the normal time, and the target The braking force cannot be generated. Therefore, in such a case, in this disc brake device, the pressing force setting means sets the friction material pressing means arranged on the outer peripheral side to a larger pressing force than the friction material pressing means arranged on the inner side. The output means causes the outer peripheral friction material pressing means to output a larger pressing force than the inner peripheral friction material pressing means. As a result, even when the friction coefficient of the friction material is reduced or the vehicle weight is increased, the same braking force as that in the normal state can be generated without increasing the energy consumption so much.

The disc brake device according to the present invention includes a caliper having a plurality of friction material pressing means that are located on at least one surface side of the disc rotor and disposed at different positions with respect to the friction material surface, and a plurality of calipers based on the target braking force. A pressing force setting unit that individually sets the pressing force of the friction material pressing unit; and a pressing force output unit that outputs each pressing force set by the pressing force setting unit to each of the friction material pressing units. The means is to set a pressing force smaller than the pressing force of the friction material pressing means arranged in the portion where the friction material is worn to the friction material pressing means arranged in the portion where the wear amount of the friction material is large. It is characterized by.

  In this disc brake device, the friction force placed on the friction material pressing means disposed in the portion where the wear amount of the friction material is large among the plurality of friction material pushing means is set by the pressing force setting means. A pressing force smaller than the pressing force of the material pressing means is set, and the pressing force output means outputs a small pressing force to the friction material pressing means at a position where the wear amount is large. For this reason, wear of the friction material with a large amount of wear is reduced, so that uneven wear can be suppressed.

  In the above-described disc brake device of the present invention, the configuration is such that the return displacement of the friction material pressing means disposed in the portion where the wear amount is large compared to the friction material pressing means disposed in the portion where the wear amount of the friction material is small is reduced. It is good.

  In this disc brake device, when the brake is turned off after being turned on, the friction material pressing means disposed in the portion where the friction material has a large wear amount is compared with the friction material pressing means disposed in the portion where the wear amount is small. Reduce the return displacement. Therefore, when the brake is off, the friction material pressing means arranged in the portion where the wear amount of the friction material is large is closer to the disk rotor than the friction material pressing means arranged in the portion where the wear amount is small, The distance between the disk rotor side surface of the friction material and the disk rotor is the same or substantially the same over the entire surface. Therefore, when the brake is turned on, in the disc brake device, if all the friction material pressing means are output with the same pressing force (displaced with the same displacement amount), the friction amount distribution of the friction material is not uniform. The friction material can be brought into contact with the disk rotor in parallel or substantially in parallel. As a result, uneven wear can be suppressed.

  According to the present invention, it is possible to appropriately control a plurality of friction material pressing means.

  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 nine pistons in each caliper, and sets a target axial force (target piston displacement) for each piston. 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 reducing brake squealing, stabilizing brake effectiveness, and suppressing uneven wear of the brake pads.

  With reference to FIG.1 and FIG.2, 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. 2A and 2B are diagrams showing the configuration of the piston of the disc brake device according to the present embodiment, in which FIG. 2A is a side view and FIG. 2B 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 a large brake pad in order to generate a large braking force. Therefore, the disc brake device 1 includes nine pistons in each caliper in order to uniformly press a large brake pad. In particular, the disc brake device 1 has nine pistons provided on each wheel in order to achieve a high level of total braking performance such as reduction of brake squealing, stabilization of braking effectiveness, and suppression of uneven wear of brake pads. Are controlled individually. For this purpose, the disc brake device 1 mainly includes a disc rotor (not shown), a caliper 2, a brake performance control device 3, an air pressure sensor 4, a pad temperature sensor 5, and first to ninth axial force sensors 6a to 6a. 6i and first to ninth displacement sensors 7a to 7i. 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. The brake pad 20 includes a friction material 20a and a back metal 20b. The friction material 20a is disposed on the disk rotor side, and the back metal 20b is attached to the back surface of the friction material 20a. The brake pad 20 on the inner side of the vehicle is provided with nine pistons 22a to 22i that come into contact with one surface of the back metal 20b. 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.

  In the present embodiment, the first to ninth pistons 22a to 22i correspond to the friction material pressing means described in the claims, and the first to ninth actuators 23a to 23i are described in the claims. It corresponds to a pressing force output means.

  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. .

  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 air pressure sensor 4 is attached to each tire (not shown). The air pressure sensor 4 detects the tire air pressure, and transmits the detected value to the brake performance control device 3 as an air pressure signal. The pad temperature sensor 5 is attached to the friction material 20 a of the brake pad 20 of each caliper 2. The pad temperature sensor 5 detects the pad temperature of the brake pad 20 and transmits the detected value to the brake performance control device 3 as a pad temperature signal.

  The brake performance control device 3 will be described with reference to FIGS. FIG. 3 is a block diagram of the squeeze reduction unit of FIG. 4A and 4B are graphs showing the state of occurrence of brake squeal, wherein FIG. 4A is a graph showing the time change of the brake hydraulic pressure, and FIG. 4B is a graph showing the time change of the brake squeal in the conventional disc brake device. (C) is a graph showing the change over time of the squeal of the brake in the disc brake device according to the present embodiment. FIG. 5 is a block diagram of the effect stabilizing unit of FIG. FIG. 6 is an explanatory diagram regarding the relationship between deceleration and vehicle weight. FIG. 7 is a friction coefficient map held by the effective stabilizing portion of FIG. FIG. 8 is a configuration diagram of the wear suppressing portion of FIG. 1. FIG. 9 is a diagram showing the relationship between the brake pad that has been unevenly worn and the amount of displacement of the piston.

  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 to ninth pistons 22 a to 22 i of the caliper 2 provided on each wheel based on the various detection signals. Are controlled independently. In particular, in the brake performance control device 3, these brakes are applied to the target axial force (target piston displacement) for each piston 22 a to 22 i in order to establish the three brake performances of brake squeal, brake effectiveness, and wear at a high level in total. The control amount for improving performance is taken into consideration. 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, a squeal reduction unit 33, an effectiveness stabilizing unit 34, and a wear suppression unit 35. The

  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. The reference target axis amount is set to the same value for the nine pistons 22a to 22i.

  The target axial force calculation unit 31 takes in the amount of change in the target axial force of the piston that changes the target axial force with respect to the reference target axial force from the squeeze reduction unit 33, the effect stabilization unit 34, and the wear suppression unit 35, respectively. The target axial force calculation unit 31 calculates the target axial force for each piston 22a to 22i by adding the target axial force change amount to the reference target axial force for the piston having the target axial force change amount. For a piston having no target axial force change amount, 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.

  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 squeeze reduction unit 33 sets two pistons and a target axial force change amount of each piston for each control cycle in order to reduce brake squeal. For that purpose, the squeeze reduction unit 33 includes a piston random selection unit 33a and a target axial force change amount calculation unit 33b. Incidentally, the brake squeal is generated in a stable state with the frictional disc rotor and the brake pad 20, and there is a condition (vibration state) that causes the brake squeal. When the sound generated by the vibration state of the disk rotor continues beyond the NG level for a long time (see the dashed elliptical area in FIG. 4B), the person feels uncomfortable and feels uncomfortable. . Therefore, two pistons randomly selected to change the vibration state every extremely short time (corresponding to a control cycle, for example, 0.5 seconds) in order to eliminate an unpleasant sound felt by humans. Gives a slight displacement.

  When it is determined that the operation of the brake pedal by the driver is started based on the control hydraulic pressure, the piston random selection unit 33a selects two pistons adjacent in the radial direction of the disk rotor from the nine pistons 22a to 22i. For example, the first piston 22a and the second piston 22b are selected. Furthermore, in the piston random selection part 33a, one piston is newly selected for every control cycle, and the newly selected piston is removed from the two control cycles, and two pistons are selected from the nine pistons 22a to 22i. select. The new selection order is the order in which the disk rotor proceeds from the inner peripheral side to the outer peripheral side in the radial direction. The pistons are selected in the order of the first piston 22a to the ninth piston 22i, and next to the ninth piston 22i. Selects the first piston 22a. For example, when the first piston 22a and the second piston 22b are selected before one control cycle, the third piston 22c is newly selected and the first piston 22a is removed, and the second piston before the one control cycle. When the piston 22b and the third piston 22c are selected, the fourth piston 22d is newly selected and the second piston 22b is removed, and the eighth piston 22h and the ninth piston 22i are selected one control period before. If it is, the first piston 22a is newly selected and the eighth piston 22h is removed.

  In the target axial force change amount calculating unit 33b, the axial force Fi (i = 1 to 9) of each piston 22a to 22i based on the axial force signal from each axial force sensor 6a to 6i is obtained by the equation (1) for each control cycle. And total axial force total F is calculated. Then, the target axial force change amount calculation unit 33b calculates the axial force change amount ΔFnaki (t) based on the total axial force total F by the equation (2) for each control cycle. The axial force change amount ΔFnaki (t) is a displacement amount when the piston is slightly displaced. Further, the target axial force change amount calculation unit 33b sets a target axial force change amount Faim (t−1) of the piston newly selected one control cycle before by the equation (3) for each control cycle. 4) The target axial force change amount Faim (t) of the piston newly selected this time is set.

  In the formula (2), “a” is a constant, for example, 0.05. (T) represents the current process, and (t-1) represents the process before one control cycle.

  The squeal reduction unit 33 outputs the numbers of the two selected pistons and the target axial force change amounts Faim (t) and Faim (t−1) corresponding to each piston to the target axial force calculation unit 31 for each control cycle. To do. Thereby, the target axial force of the piston newly selected this time increases by ΔFnaki (t) with respect to the reference target axial force. On the other hand, the target axial force of the piston newly selected every control cycle decreases by ΔFnaki (t) with respect to the reference target axial force. Further, the squeeze reduction unit 33 outputs a command for returning the target axial force of the newly selected piston to the reference target axial force every two control cycles to the target axial force calculation unit 31.

  In this way, there are portions where the axial force of the piston increases and portions (a portion where the piston displacement is large and a portion where the piston displacement is large) along the radial direction of the disk rotor. It changes slightly. Therefore, sounds having different frequencies are generated as brake squeals for each control cycle. As shown in FIG. 4 (c), sounds having different frequencies may exceed the NG level. However, since the tone changes and lasts for a very short time, it is possible to prevent the brake squeal from continuing.

  The effect stabilizing unit 34 sets the target axial force change amount of the pistons 22c, 22f, and 22i on the outer peripheral side in order to stabilize the effect of the brake even when the temperature of the brake pad 20 changes or the vehicle weight changes. To do. Therefore, the effectiveness stabilizing unit 34 includes a braking torque estimating unit 34a, a friction coefficient estimating unit 34b, and a target axial force change amount calculating unit 34c (see FIG. 5). Incidentally, when the temperature of the brake pad 20 changes, the friction coefficient of the brake pad changes, so that the braking force changes even if the axial force of the piston is the same. Further, when the vehicle weight increases, the braking force decreases even if the axial force of the piston is the same. Accordingly, even when the driver's brake pedal operation amount is the same, the braking force changes when the temperature of the brake pad 20 or the vehicle weight changes. Therefore, the deceleration changes, the feeling of deceleration received by the driver changes, and the braking feeling deteriorates. Therefore, in order to generate a stable braking force corresponding to the amount of operation of the brake pedal even when the temperature of the brake pad and the vehicle weight change, the axial force (displacement) of the pistons 22c, 22f, 22i on the outer peripheral side is generated. Change the braking torque.

  The relationship between the deceleration and the vehicle weight will be described with reference to FIG. FT is a force acting on the road surface from the tire, and is a multiplication value of the vehicle weight W applied to the tire (wheel) and the deceleration β as shown in the equation (5). As shown in the equation (6), the deceleration β is proportional to the vehicle weight W applied to the tire.

  FP is a pressing force against the brake pad 20 and corresponds to the axial force of all the pistons 22a to 22i. RD is the rotor effective radius from the center of the disk rotor to the center of the position where the brake pad is pressed, and is the average value of the distance (radius Ri) from the center of the disk rotor to the center of each piston. RT is the radius of the tire.

  The braking torque estimation unit 34a takes in an air pressure signal from the air pressure sensor 4 of each wheel, and calculates a vehicle weight W applied to each wheel from the tire air pressure. Further, the braking torque estimation unit 34a calculates the load change amount ΔW of each wheel by subtracting the reference vehicle weight Wb from the vehicle weight W applied to each wheel according to the equation (7). Then, the braking torque estimation unit 34a calculates the braking torque change amount ΔT necessary for each wheel from the load change amount ΔW of each wheel by the equation (8). This braking torque change amount ΔT is a change amount of the braking torque necessary to prevent the braking effectiveness (braking force) from changing even when the vehicle weight changes due to increase or decrease of the occupant. As a means for detecting the vehicle weight, other detection means may be used instead of the air pressure sensor.

  G in Expression (8) is a reference braking force when the reference brake pedal is operated when the reference vehicle weight (for example, the vehicle weight when two adult males are riding) is a constant value. fl represents the left front wheel, fr represents the right front wheel, rl represents the left rear wheel, and rr represents the right rear wheel.

  The friction coefficient estimator 34b takes in the pad temperature signal from the pad temperature sensor 5 for each wheel and takes in the axial force signals from the axial force sensors 6a to 6i for each wheel. Then, the friction coefficient estimating unit 34b for each wheel uses the brake pad 20 (friction) based on the total axial force F obtained by integrating the pad temperature and the axial force Fi of each piston 22a to 22i from the friction coefficient map held in the ROM. The friction coefficient μ of the material 20a) is obtained. As shown in FIG. 7, in the friction coefficient map, the friction coefficient of the brake pad that changes with respect to the pad temperature is set for each axial force of the piston in a plurality of stages.

  The target axial force change amount calculation unit 34c uses the braking torque change amount ΔT and the friction coefficient μ required for each wheel for each wheel, so that the target of each piston 22a to 22i is satisfied so that the condition of Expression (9) is satisfied. The axial force change amount ΔFki is set. At this time, the target axial force change amount ΔFki is set so that the energy consumption for operating the pistons 22a to 22i is minimized. For this purpose, the target axial force change amount calculation unit 34c sets the target axial force change amount ΔFki so as to satisfy the condition of Expression (10). In order to satisfy the condition of Expression (10), it is necessary to reduce the energy consumption for operating the pistons 22a to 22i as much as possible. Therefore, the third piston 22c, the sixth piston 22f, and the ninth piston 22i on the outer peripheral side The value of each target axial force change amount ΔFk3, ΔFk6, ΔFk9 is increased. At this time, the axial force of the pistons 22c, 22f, and 22i on the outer peripheral side may be increased, and the axial force of the pistons 22a, 22d, and 22g on the inner peripheral side may be decreased. Note that the axial force of the pistons 22c, 22f, and 22i on the outer peripheral side may be reduced.

  Ri in Expression (9) is a distance from the center of the disk rotor to the center of each piston 22a to 22i, and indicates a radius with respect to each piston 22a to 22i. i shows the piston number of each piston 22a-22i.

  The effect stabilizing unit 34 outputs a target axial force change amount ΔFki for each of the pistons 22a to 22i (particularly, the outer peripheral side pistons 22c, 22f, and 22i) to the target axial force calculating unit 31 for each wheel. Therefore, when the vehicle weight changes from the reference vehicle weight or when the pad temperature changes, the target axial force of the pistons 22c, 22f, and 22i on the outer peripheral side increases (decreases) by ΔFki with respect to the reference target axial force. There is also). In this way, by changing the axial force of the pistons 22c, 22f, and 22i on the outer peripheral side, a stable braking force is generated for a predetermined operation amount on the brake pedal regardless of the pad temperature and the vehicle weight condition. be able to.

  In order to suppress uneven wear of the brake pad 20 (friction material 20a), the wear suppression unit 35 corresponds to the amount of wear at each portion when uneven wear occurs, and the amount of change in the target axial force of the piston. Set. Therefore, the wear suppression unit 35 includes a pad shape estimation unit 35a and a target axial force change amount calculation unit 35b. Incidentally, since the braking force is generated by the friction between the friction material 20a and the disk rotor, the friction material 20a increases in wear amount as the usage time increases, and the difference in wear amount (uneven wear) also in each part. appear. The uneven wear cannot stabilize the friction between the disc rotor and the brake pad, and adversely affects other brake performance. In addition, the volume of the friction material 20a cannot be used effectively, and must be replaced early. Therefore, the uneven wear is detected, and when the uneven wear occurs, the displacement amount of each piston is changed so as to reduce the difference in the wear amount.

  The pad shape estimation unit 35a takes in a pad temperature signal from the pad temperature sensor 5 and determines whether or not the pad temperature is lower than a reference temperature. Here, since the shape of the brake pad 20 (friction material 20a) is estimated, it is necessary to eliminate the influence of the thermal expansion of the friction material 20a. Therefore, by determining whether or not the pad temperature is lower than the reference temperature, the shape of the brake pad 20 is estimated in a normal temperature region where thermal expansion does not occur.

  When the pad temperature is lower than the reference temperature, the pad shape estimation unit 35a incorporates the axial force signals from the axial force sensors 6a to 6i and the displacement signals from the displacement sensors 7a to 7i. And in the pad shape estimation part 35a, it is determined whether the axial force of each piston 22a-22i is larger than contact axial force. Here, the shape of the brake pad 20 (friction material 20a) is estimated according to how much each piston 22a-22i is displaced before each part of the brake pad 20 contacts the disk rotor. Therefore, it is necessary to determine whether each portion of the brake pad 20 pressed by each piston 22a to 22i has contacted the disk rotor. Therefore, it is determined whether or not each part of the brake pad 20 is in contact with the disc brake by determining whether or not each axial force of the pistons 22a to 22i is larger than the contact axial force. Incidentally, when the brake pad 20 comes into contact with the disk rotor, the axial force of the pistons 22a to 22i is obviously larger than that when the brake pad 20 is separated.

  When the axial force of the piston with the pistons 22a to 22i becomes larger than the contact axial force, the pad shape estimation unit 35a stores the displacement amount of the piston. The pad shape estimation unit 35a continues this determination until the axial force of all the pistons 22a to 22i becomes larger than the contact axial force, and stores the displacement amounts for all the pistons 22a to 22i. Thereby, the displacement amount of each piston 22a-22i when each part of the brake pad 20 contacts the disc brake is detected, and the shape (wear shape) of the brake pad 20 (friction material 20a) is determined by these nine displacement amounts. Can be estimated. When uneven wear occurs, the amount of displacement of the piston that presses the portion of the friction material 20a with a large amount of wear increases, and the portion with a small amount of wear of the friction material 20a presses that portion. The displacement amount of the piston is small (see FIG. 9).

  The pad shape estimation unit 35a calculates an average value (average piston displacement amount) of the nine displacement amounts stored. And in the pad shape estimation part 35a, the average piston displacement is subtracted from each memorize | stored displacement, and each wear amount Di in the part which each piston 22a-22i is pressing is calculated. Further, the pad shape estimation unit 35a calculates an average value (average wear amount) Dave of the obtained nine wear amounts Di. When the wear amount Di (i = 1 to 9) is a positive value, the wear amount is larger than the average wear amount in the friction material 20a, and when the wear amount Di is negative, the wear amount is smaller than the average wear amount. The larger the difference between the maximum wear amount Di-max and the minimum wear amount Di-min, the greater the uneven wear.

  In the target axial force change amount calculation unit 35b, the minimum wear amount Di-min is subtracted from the maximum wear amount Di-max, and this subtracted value is used as the uneven wear amount. Then, the target axial force change amount calculation unit 35b determines whether or not the uneven wear amount is larger than the uneven wear determination value (for example, 100 μm). If the amount of displacement between each of the pistons 22a to 22i is changed when uneven wear has not occurred or when uneven wear is small, problems such as the rotor falling over which the disk rotor is inclined with respect to the brake pad 20 occur. Therefore, the target axial force change amount of each piston 22a to 22i is set only when a large amount of uneven wear occurs to some extent. When the uneven wear amount is larger than the uneven wear determination value, the target axial force change amount calculation unit 35b uses the equation (11) to calculate the target of each piston 22a to 22i from the wear amount Di and the average wear amount Dave of each piston 22a to 22i. An axial force change amount ΔFmi is calculated.

  In Formula (11), Fi is the axial force of each piston 22a-22i by the 1st-9th axial force signal.

  The wear suppression unit 35 outputs the target axial force change amount ΔFmi of each of the pistons 22 a to 22 i to the target axial force calculation unit 31. Thereby, the axial force of each piston 22a-22i turns into an axial force according to the wear amount of the friction material 20a, the axial force of a part with much wear amount is small, and the axial force of a part with little wear amount becomes large. As a result, the wear of the portion with a large wear amount of the friction material 20a is reduced. Further, the displacement amount of each piston 22a to 22i is the displacement amount along the uneven wear of the brake pad 20 (friction material 20a), the piston displacement amount in the portion where the wear amount is large becomes large, and the displacement amount in the portion where the wear amount is small. Becomes smaller (see FIG. 9). As a result, when the brake is on, the surface of the brake pad 20 on the disk rotor side is parallel or substantially parallel to the disk rotor.

  Further, when it is determined that the operation of the brake pedal by the driver is completed based on the control hydraulic pressure, the wear suppression unit 35 determines whether or not the axial force of each piston 22a to 22i is separated and smaller than the axial force. Here, when uneven wear occurs and the displacement amount of each piston 22a to 22i is changed to suppress the uneven wear, the return amount of all the pistons 22a to 22i is made constant. Therefore, it is determined whether each part of the brake pad 20 is separated from the disc brake by determining whether each axial force of the pistons 22a to 22i is smaller than the separated axial force. Incidentally, the axial force of the pistons 22a to 22i is obviously smaller when the brake pad 20 is separated from the disk rotor than when it is in contact.

  When the axial force of the piston with the pistons 22a to 22i is separated and smaller than the axial force, the wear suppression unit 35 outputs a command for returning the return amount of the piston by a constant amount to the target piston displacement calculation unit 32. The wear suppression unit 35 continues this determination until the axial force of all the pistons 22a to 22i is separated and becomes smaller than the axial force, and outputs a command for all the pistons 22a to 22i to the target piston displacement calculation unit 32. As a result, when the brake is off, the tip of each piston 22a to 22i stops at a position along the uneven wear of the brake pad 20 (friction material 20a), and the tip of the piston with a large amount of wear is close to the disk rotor. Therefore, the tip of the piston with a small amount of wear becomes far from the disk rotor. Even when the brake pad 20 (friction material 20a) is unevenly worn when the brake is off, the surface of the brake pad 20 on the disk rotor side is parallel or substantially parallel to the disk rotor. Therefore, when all the pistons 22a to 22i are displaced by the same displacement amount (the same axial force) at the time of brake on, the brake pad 20 comes into contact with the disk rotor in parallel or substantially in parallel. Note that the fixed return amount may be set to a predetermined value, or may be the displacement amount of the piston with the average wear amount.

  The operation of the disc brake device 1 will be described with reference to FIG. In particular, the processing in the squeeze reduction unit 33 will be described along the flowchart of FIG. 10, the processing in the effectiveness stabilizing unit 34 will be described along the flowchart of FIG. 11, and the processing in the wear suppression unit 35 will be described in the flowchart of FIG. It explains along. FIG. 10 is a flowchart showing the flow of processing in the squeeze reduction unit of FIG. FIG. 11 is a flowchart showing the flow of processing in the effect stabilizing section of FIG. FIG. 12 is a flowchart showing the flow of processing in the wear suppression 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 amounts Faim (t) and Faim (t−1) of the two pistons by the squeeze reduction unit 33, and the pistons 22 a to 22 i ( In particular, the target axial force change amount ΔFki of the outer peripheral pistons 22c, 22f, and 22i) and the target axial force change amount ΔFmi of the pistons 22a to 22i by the wear suppression unit 35 are added to the reference target axial force, respectively. The target axial force of ˜22i is calculated respectively. Incidentally, the target axial force change amount ΔFmi by the wear suppression unit 35 is set only when uneven wear occurs. 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 each part of the inner brake pad 20 is pressed. Eventually, the surface on the disc rotor side of the inner brake pad 20 comes into contact with the disc rotor, and the brake pad 20 presses the disc 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 squeeze reduction unit 33 determines that the brake is turned on based on the control hydraulic pressure (S10), the two pistons having consecutive numbers are randomly selected from the nine pistons 22a to 22i (S11). Subsequently, the squeeze reduction unit 33 calculates the total axial force total F from the detected axial force Fi of each of the pistons 22a to 22i, and the axial force change amount ΔFnaki (t) from the total axial force total F by equation (2). Is calculated (S12). Further, the squeal reduction unit 33 obtains and selects the target axial force change amount Faim (t) of the piston by the equation (3) in order to increase the axial force of the piston having the largest piston number among the selected pistons. In order to reduce the axial force of the piston having the smallest piston number, the target axial force change amount Faim (t-1) of the piston is obtained by equation (4) (S13). Here, the squeal reducing unit 33 determines whether or not one control cycle has elapsed, and waits until one control cycle has elapsed (S14).

  When one control cycle elapses, the squeal reducing unit 33 selects a piston having a number one larger than the piston selected before one control cycle in order to select a piston along the radial direction of the disk rotor (S15). Subsequently, the squeal reducing unit 33 calculates the axial force change amount ΔFnaki (t), similarly to S12 (S16). The squeeze reduction unit 33 returns the target axial force of the piston whose axial force has been reduced every control cycle to the reference. Further, the squeeze reducing unit 33 obtains the target axial force variation Faim (t−1) of the piston by the equation (4) in order to reduce the axial force of the piston whose axial force is increased every control cycle, In order to increase the axial force of the piston selected this time, the target axial force change amount Faim (t) of the piston is obtained by equation (3) (S18). Here, the squeal reducing unit 33 determines whether or not one control cycle has elapsed, and waits until one control cycle has elapsed (S19).

  Then, the squeeze reduction unit 33 determines whether or not the brake is turned off based on the control hydraulic pressure, repeatedly executes the processes of S15 to S19 until the brake is turned off, and ends the process when the brake is turned off (S20). .

  At this time, in the brake performance control device 3, the target axial force change amount Faim (t−1) is set to the target axial force of the piston having the smaller number of the two pistons selected by the squeeze reducing unit 33 for each control cycle. The target axial force of the piston with the larger number is increased by the target axial force change amount Faim (t). As a result, at each control cycle, the portion where the axial force of the piston increases and the portion where the axial force decreases move along the radial direction of the disk rotor, and the vibration state in the axial direction of the disk rotor changes slightly. Therefore, brake squeals (tones) with different frequencies change in a very short time.

  Further, when the effectiveness stabilizing unit 34 determines that the brake is turned on based on the control oil pressure (S30), the vehicle weight W applied to each wheel is estimated from the detected value of the air pressure of each tire (S31). Subsequently, the effect stabilizing unit 34 calculates the load change amount ΔW of each wheel with respect to the reference vehicle weight Wb of the vehicle weight W applied to each wheel according to the equation (7) (S32). Further, the effectiveness stabilizing unit 34 calculates the braking torque change amount ΔT required for each wheel from the load change amount ΔW of each wheel according to the equation (8) (S33).

  The effect stabilizing unit 34 acquires the pad temperature from the pad temperature signal from the pad temperature sensor 5 for each wheel, and acquires the axial force Fi of each piston 22a to 22i from the axial force signal from each axial force sensor 6a to 6i. (S34). The effectiveness stabilizing unit 34 acquires the friction coefficient μ of the brake pad 20 (friction material 20a) from the total axial force F obtained by integrating the pad temperature and the axial force Fi on the basis of the friction coefficient map for each wheel ( S35). Further, in the effect stabilizing portion 34, the outer peripheral piston 22c is obtained in order to obtain an axial force that supplements the braking torque change amount ΔT necessary for each wheel so that the conditions of the equations (9) and (10) are satisfied. , 22f, and 22i, the target axial force change amount ΔFki is calculated (S36).

  The effectiveness stabilizing unit 34 determines whether or not the brake is turned off based on the control hydraulic pressure, repeatedly executes the processes of S34 to S36 until the brake is turned off, and ends the process when the brake is turned off (S37). .

  At this time, in the brake performance control device 3, the target axial force of the pistons 22c, 22f, and 22i on the outer peripheral side is changed by the target axial force change amount ΔFki set by the stabilization unit 34, respectively. As a result, the outer side pistons 22c, 22f, and 22i can generate an axial force that compensates for the required brake torque change amount ΔT in accordance with changes in the pad temperature (and hence changes in the friction coefficient μ) and changes in the vehicle weight. The same braking force (and hence deceleration) can be generated for the same brake pedal operation amount.

  Further, when it is determined that the brake is turned on based on the control hydraulic pressure (S40), the wear suppression unit 35 acquires the pad temperature based on the pad temperature signal from the pad temperature sensor 5 (S41). Then, the wear suppression unit 35 determines whether or not the pad temperature is lower than the reference temperature. If the pad temperature is equal to or higher than the reference temperature, the process returns to S40 (S42).

  When the pad temperature is lower than the reference temperature, the wear suppressing unit 35 determines whether or not there is a piston whose wear shape estimation flag is 0, and if not, the process returns to S40 (S43). The wear shape estimation flag is provided for each of the pistons 22a to 22i. In the case of 1, the displacement amount of the piston for estimating the piston shape is stored. In the case of 0, the displacement of the piston is stored. The amount is not remembered.

  When there is a piston whose wear shape estimation flag is 0, the wear suppression unit 35 calculates the piston axial force based on the axial force signals from the axial force sensors 6a to 6i and the piston displacement by the displacement sensors from the displacement sensors 7a to 7i, respectively. Obtain (S44). Then, the wear suppression unit 35 determines whether or not the axial force of each of the pistons 22a to 22i is larger than the contact axial force, and if there is no piston having an axial force larger than the contact axial force, the process returns to S44 ( S45).

  When there is a piston with an axial force larger than the contact axial force, the wear suppression unit 35 stores the displacement amount of the piston (S46) and sets 1 to the wear shape estimation flag of the piston (S47). Then, the wear suppression unit 35 determines whether or not the axial force of all the pistons 22a to 22i is larger than the contact axial force. If the axial force of all the pistons 22a to 22i is not larger than the contact axial force, S44 is performed. Return to the process (S48). Here, with respect to all the pistons 22a to 22i, the displacement amount of the piston when each part of the brake pad 20 pressed by each piston comes into contact with the disc brake is stored.

  When the axial force of all the pistons 22a to 22i is larger than the contact axial force, the wear suppression unit 35 calculates the average piston displacement amount from the nine stored displacement amounts, and the difference between each displacement amount and the average piston displacement amount. To calculate the wear amount Di at the portion where each piston 22a to 22i is pressed (S49). Further, the wear suppression unit 35 calculates an average wear amount Dave of the nine wear amounts Di. Based on the nine wear amounts Di for the brake pad 20 (friction material 20a), the degree of wear at each portion where the pistons 22a to 22i are pressed on the brake pad 20 is known, and it can be determined whether or not there is uneven wear. . Therefore, the wear suppression unit 35 subtracts the minimum wear amount Di-min from the maximum wear amount Di-max among the nine wear amounts Di, and this subtraction value (uneven wear amount) is larger than the uneven wear determination value. It is determined whether or not (S50). When the amount of uneven wear is equal to or less than the uneven wear determination value, the uneven wear is not so severe as to suppress the uneven wear, and the wear suppressing unit 35 returns to the process of S40.

  When the uneven wear amount is larger than the uneven wear determination value, the wear suppression unit 35 calculates the target axial force change amount of each piston 22a to 22i from the wear amount Di and the average wear amount Dave of each piston 22a to 22i by the equation (11). ΔFmi is calculated (S51). This target axial force change amount ΔFmi increases the axial force of the piston pressing the portion where the wear amount Di is smaller than the average, and decreases the axial force of the piston pressing the portion where the wear amount Di is larger than the average. This is the target axial force change amount. Thereby, the axial force of each piston 22a-22i turns into an axial force according to the wear amount of the friction material 20a, the axial force of a part with much wear amount is small, and the axial force of a part with little wear amount becomes large.

  At this time, in the brake performance control device 3, the target axial force of each piston 22 a to 22 i is changed by the target axial force change amount ΔFmi set by the wear suppression unit 35. Thereby, each piston 22a-22i is each displaced according to the amount of wear in each part of brake pad 20 (friction material 20a), and the surface by the side of the disc rotor of brake pad 20 is parallel or almost to the disc rotor. Parallel.

  Further, the wear suppression unit 35 determines whether or not the brake is turned off based on the control oil pressure, and waits until the brake is turned off (S52). When the brake is turned off and each piston 22a to 22i is operated in the returning direction (S53), the wear suppression unit 35 determines whether or not the axial force of each piston 22a to 22i is smaller than the separated axial force. If there is no piston having an axial force smaller than the force, the process returns to S53 (S54).

  When there is a piston with an axial force smaller than the separation axial force, the wear suppression unit 35 makes the return amount of the piston constant (S55). The wear suppression unit 35 determines whether or not all the pistons 22a to 22i have been returned by a certain amount. If all the pistons 22a to 22i have not been returned by a certain amount, the process returns to S53 (S56). When all the pistons 22a to 22i are returned by a certain amount, the wear suppression unit 35 sets the wear shape estimation flags of all the pistons 22a to 22i to 0 (S57).

  At this time, the brake performance control device 3 returns all the pistons 22a to 22i by a certain amount after each part of the brake pad 20 pressed by each piston leaves the disc brake. Thereby, at the time of brake-off, each piston 22a-22i has returned to each position according to the abrasion amount in each part of the brake pad 20 (friction material 20a), and the disk rotor side surface of the brake pad 20 is the disk. Parallel or nearly parallel to the rotor.

  According to this disc brake device 1, the axial force (piston displacement) can be set independently for each of the plurality of pistons 22a to 22i, and the axial force of each piston 22a to 22i can be improved in order to improve the braking performance. Can be changed individually. Therefore, in the disc brake device 1, the brake performance such as brake squealing, braking effectiveness, and wear can be established in a high dimension in total.

  In particular, the disc brake device 1 can prevent the brake squeal from continuing by moving the part where the axial force of the piston slightly increases and the part where the axial force of the piston slightly decreases every extremely short time, thereby reducing the brake squeal. Furthermore, in the disc brake device 1, the vibration state of the disc rotor can be changed with high efficiency by selecting a piston that slightly increases the axial force along the radial direction of the disc rotor.

  Further, in the disc brake device 1, even when the pad temperature and the vehicle weight change, the same braking force is applied to the same brake pedal operation amount by changing the axial force of the pistons 22c, 22f, and 22i on the outer peripheral side. Can be generated. Therefore, for the same brake pedal operation amount, the driver always receives the same feeling of deceleration and has a good braking feeling. Further, in the disc brake device 1, since the axial force of the pistons 22c, 22f, and 22i on the outer peripheral side is changed, the energy for operating the piston is minimized and the energy consumption efficiency is high. Moreover, the amount of wear of the brake pad 20 (friction material 20a) can also be reduced.

  Further, the disc brake device 1 can determine whether or not uneven wear occurs in the brake pad 20 (friction material 20a). If uneven wear occurs, the pistons 22a to 22i correspond to the amount of wear. Uneven wear can be suppressed by changing the axial force. Further, in the disc brake device 1, when uneven wear occurs, the return amount of each piston 22a to 22i is made constant, so that at the next brake-on, all the pistons 22a to 22i are moved by the same displacement amount to the brake pad 20. Can be brought into contact with the disk rotor in parallel, and uneven wear can be suppressed.

  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, although the disc brake device is applied to an automobile in the present embodiment, 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 configuration includes nine 3 × 3 pistons for one brake pad. However, considering the shape and size of the brake pad, the piston radius, and the like, the number and arrangement of pistons are appropriately determined. May be set.

  In this embodiment, the squeal reducing unit, the effect stabilizing unit, and the wear suppressing unit are provided and the target axial force change amount is set in each processing unit. However, not all of these three processing units are provided. It is good also as a structure which has only two process parts or one process part. Moreover, it is good also as a structure which has a process part which sets the target axial force variation | change_quantity for improving brake performance other than these, such as vibration suppression.

  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 the present embodiment, the squeeze reduction unit randomly selects two brake pads, and then selects one brake pad along the radial direction of the disk rotor for each control cycle. Two brake pads may be selected at random for each cycle, or the brake pads may be selected according to another selection order instead of the radial direction of the disk rotor for each control cycle.

  Further, in the present embodiment, the squeeze reduction unit is configured to control every constant control cycle, but may be configured to control every arbitrary control cycle. In this case, since the occurrence condition (vibration state) of the brake squeal can be changed every random time, the brake squeal can be prevented from being sustained and the brake squeal can be reduced.

  Further, in the present embodiment, it is configured to control the braking torque to be kept constant when the vehicle weight changes in the effective stabilizing portion, but if there is a factor that affects the braking torque in addition to the vehicle weight, The braking torque may be kept constant when the factor changes.

  In the present embodiment, the wear suppression unit performs control for setting the target axial force change amount (and hence the target axial force) of each piston according to the wear amount and control for making the piston return displacement constant after the brake is turned off. However, in this case, there is an effect of suppressing wear.

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 the structure of the piston of the disc brake apparatus which concerns on this Embodiment, (a) is a side view, (b) is a front view. It is a block diagram of the squeeze reduction part of FIG. It is a graph which shows the occurrence situation of a brake squeal, (a) is a graph which shows a time change of braking oil pressure, (b) is a graph which shows a time change of the squeal of a brake in the conventional disc brake device, (c) is a graph which shows the time change of the squeal of the brake in the disc brake device which concerns on this Embodiment. It is a block diagram of the effect stabilizing part of FIG. It is explanatory drawing about the relationship between deceleration and vehicle weight. It is a friction coefficient map hold | maintained at the effect stable part of FIG. It is a block diagram of the abrasion suppression part of FIG. It is a figure which shows the relationship between the brake pad which carried out uneven wear, and the displacement amount of a piston. It is a flowchart which shows the flow of a process in the noise reduction part of FIG. It is a flowchart which shows the flow of a process in the effect stabilization part of FIG. It is a flowchart which shows the flow of a process in the abrasion suppression part of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Disc brake device, 2 ... Caliper, 3 ... Brake performance control device, 4 ... Air pressure sensor, 5 ... Pad temperature sensor, 6a-6i ... 1st-9th axial force sensor, 7a-7i ... 1st-9th Displacement sensor, 20 ... brake pad, 20a ... friction material, 20b ... 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 ... Squeal reduction unit 33a ... Piston random selection unit 33b ... Target axial force change amount calculation unit 34 ... Effective stabilization unit 34a ... Brake torque estimation unit 34b: Friction coefficient estimation unit, 34c ... Target axial force change amount calculation unit, 35 ... Wear suppression unit, 35a ... Pad shape estimation unit, 35b ... Target axial force change amount calculation unit

Claims (9)

A caliper having a plurality of friction material pressing means located on at least one surface side of the disk rotor and arranged at different positions with respect to the friction material surface;
The plurality of friction material pressing means in consideration of the target axial force change amount calculated for at least one of squeal reduction, effectiveness stabilization, and wear suppression with respect to a reference target axial force based on the control hydraulic pressure Pressing force setting means for individually setting the pressing force;
A disc brake device comprising: a pressing force output unit that outputs each pressing force set by the pressing force setting unit to each of the plurality of friction material pressing units.   The pressing force setting unit arbitrarily selects a different friction material pressing unit every predetermined time, and sets a pressing force having a magnitude different from that of the other friction material pressing unit to the selected friction material pressing unit. 2. The disc brake device according to claim 1, wherein   The pressing force setting means selects a friction material pressing means having a different radial position of the disk rotor every predetermined time, and presses the selected friction material pressing means with a different size from that of the other friction material pressing means. 2. The disc brake device according to claim 1, wherein the pressure is set.   The pressing force setting means sets a pressing force having a magnitude different from that of other friction material pressing means to an arbitrary friction material pressing means among the plurality of friction material pressing means at an arbitrary time. The disc brake device according to claim 1.   The pressing force setting means selects two friction material pressing means among the plurality of friction material pressing means, and is increased from the other friction material pressing means not selected as one of the selected friction material pressing means. The pressed force is set, and the pressed force that reduces the increased pressing force is set to the other friction material pressing means among the selected friction members. Disc brake device described in the paragraph.   The pressing force setting means sets a pressing force larger than the friction material pressing means arranged on the inner peripheral side to the friction material pressing means arranged on the outer peripheral side with respect to the radial direction of the disk rotor. The disc brake device according to claim 1.   The pressing force setting means is a friction material pressing means arranged on the outer peripheral side with respect to the radial direction of the disc rotor when the friction coefficient of the friction material is lower than the reference value or when the vehicle weight is increased from the reference value. 7. The disc brake device according to claim 6, wherein a pressing force larger than that of the friction material pressing means disposed on the inner peripheral side is set. A caliper having a plurality of friction material pressing means located on at least one surface side of the disk rotor and arranged at different positions with respect to the friction material surface;
A pressing force setting means for individually setting the pressing force of the plurality of friction material pressing means based on a target braking force;
A pressing force output means for causing each of the plurality of friction material pressing means to output each pressing force set by the pressing force setting means;
With
The pressing force setting means has a pressing force smaller than the pressing force of the friction material pressing means disposed in the portion where the friction material pressing amount is disposed on the friction material pressing means disposed in the portion where the friction material wear amount is large. A disc brake device characterized by setting.   2. The return displacement of the friction material pressing means disposed in a portion where the wear amount is large compared with the friction material pressing means disposed in a portion where the wear amount of the friction material is small. Item 9. The disc brake device according to Item 8.

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