JP2008057677A - State detecting device of brake disc - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a state detecting device of a brake disc capable of detecting microscopic biased abrasion of the brake disc. <P>SOLUTION: This state detecting device of the brake disc 20 brakes rotation of a wheel by pressing a friction material to a surface, and has temperature distribution detecting means 50 and 60 detecting the temperature distribution in the peripheral direction of the brake disc 20. When an abrasion quantity of the brake disc 20 is small (thick), a temperature change is large since the friction material 30 is strongly pressed, and when the abrasion quantity of the brake disc 20 is large (thin), the temperature change is small since the friction material 30 is not strongly pressed. Thus, a state of the brake disc 20 can detect further microscopic partial abrasion more than when detecting the state by measuring a variation in hydraulic pressure, by detecting the temperature distribution in the peripheral direction of the brake disc 20, in an easily appearing place as the temperature distribution in the peripheral direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a brake disk state detection device.

As an apparatus for detecting the thickness state of a brake disk, for example, there is one disclosed in Patent Document 1. In this device, the hydraulic pressure fluctuation in the wheel cylinder is detected, the thickness difference of the brake disc is obtained based on this, and the brake hydraulic pressure is adjusted so as to eliminate this difference.
JP 2001-130393 A

  However, it is difficult to detect minute uneven wear by measuring the fluctuation of the hydraulic pressure using a torque sensor or a hydraulic pressure sensor.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brake disk state detection device that can detect minute uneven wear of a brake disk.

  A brake disk state detection device according to the present invention is a brake disk state detection device for braking the rotation of a wheel by pressing a friction material on the surface, and detecting the temperature distribution in the circumferential direction of the brake disk. A distribution detecting means is provided.

  When the amount of wear on the brake disc is small (thick), the friction material is pressed strongly, so the temperature change is large. On the other hand, when the amount of wear on the brake disc is large (thin), the friction material is not pressed strongly. Small temperature change. Thus, the state of the brake disk is likely to appear as a circumferential temperature distribution. However, the apparatus according to the present invention can detect the surface state by detecting the temperature distribution in the circumferential direction of the brake disk. Compared with the case where the state is detected by measuring the fluctuations in this, it is possible to detect a minute uneven wear.

  It is preferable that the temperature distribution detection means has an integration means for integrating the temperature distributions detected at different times. In this way, even if the deviation of the temperature distribution is small, the deviation can be increased by integration, so that minute uneven wear can be detected more reliably. In particular, the detection of brake drag is particularly suitable because the temperature distribution has a very small deviation.

  The temperature distribution detecting means includes a temperature sensor, and the temperature sensor is preferably arranged on both the inner surface side and the outer surface side of the brake disc. By doing so, it is possible to separately detect the surface state of the inner surface side and the outer surface side of the brake disc, and for example, it is possible to specify the surface where the brake disc is dragged.

  ADVANTAGE OF THE INVENTION According to this invention, the brake disk state detection apparatus which makes it possible to detect the minute uneven wear of a brake disk can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a diagram schematically illustrating a braking device 10 including a brake disk state detection device according to the present embodiment. As shown in FIG. 1, the braking device 10 includes a brake disk 20, a pair of brake pads 30, a wheel cylinder 40, a pair of temperature sensors 50, a rotational position sensor 60, and a brake ECU 70.

  The brake disc 20 has a substantially disk shape and is provided on each wheel of the vehicle. A pair of brake pads 30 that are friction materials are provided on the inner surface side and the outer surface side of the brake disc 20, and are pressed against the brake disc 20 by the hydraulic pressure of the wheel cylinder 40, and the pressure is released or controlled.

  The pair of temperature sensors 50 are provided on the inner surface side and the outer surface side of the brake disc 20 and detect the temperature of the brake disc 20 on each side. The temperature sensor 50 is preferably one that can be detected without contact, and examples thereof include an infrared sensor.

  The rotational position sensor 60 detects the rotational position (that is, the rotational angle) of the brake disc 20 and includes, for example, a wheel speed sensor.

  The brake ECU 70 controls braking, and controls the brake pad 30 via a data storage unit 70 a that stores various data, a calculation unit 70 b that performs various calculations, a determination unit 70 c that performs various determinations, and a wheel cylinder 40. A hydraulic pressure control unit 70d is provided. The brake ECU 70 is electrically connected to the brake pedal 80, and the hydraulic pressure controller 70 d controls the brake pad 30 by applying hydraulic pressure based on a signal from the brake pedal 80.

  The data storage unit 70a stores the temperature data detected by the temperature sensor 50 in association with the rotational position of the brake disk 20 detected by the rotational position sensor 60. The calculation unit 70b calculates the average temperature of one revolution of the brake disk 20, calculates the average temperature change of one rotation, and calculates the temperature change of one rotation. The calculation unit 70b also integrates the temperature distribution in the circumferential direction of the brake disc 20 detected at different times, and calculates a correction hydraulic pressure for correcting uneven wear of the brake disc 20. The hydraulic pressure control unit 70d controls the wheel cylinder 40 so as to load the corrected hydraulic pressure calculated by the calculation unit 70b.

  In the present embodiment, the temperature sensor 50 and the rotational position sensor 60 constitute a temperature distribution detection means. Further, the calculating unit 70b of the brake ECU 70 constitutes an integrating unit, and the temperature distribution detecting unit can include such an integrating unit. By providing the temperature distribution detecting means in this way, a brake disk state detecting device is configured.

  Next, a method for correcting braking torque fluctuation and drag torque fluctuation including detection of uneven wear of the brake disc 20 by the braking device 10 will be described with reference to FIGS.

  FIG. 2 is a flowchart showing a method of correcting braking torque fluctuation caused by uneven wear of the brake disk 20, and FIG. 3 is a flowchart showing a method of correcting drag torque fluctuation caused by uneven wear of the brake disk 20. FIG. 4 is a flowchart showing a subroutine for correcting braking torque fluctuation and drag torque fluctuation caused by uneven wear of the brake disc 20.

  As shown in FIG. 2, in correcting the braking torque fluctuation, first, in step S201, it is determined in the determination unit 70c of the brake ECU 70 whether or not the brake is on. If it is determined that the brake is on, in step S202, the determination unit 70c determines whether or not the travel distance from the previous measurement is equal to or greater than the predetermined distance Lkm. As this distance Lkm, the travel distance in which uneven wear occurs is obtained and set in advance according to the travel conditions. And if it determines with the travel distance from the last measurement being less than the predetermined distance Lkm, a process will be stopped. On the other hand, if it is determined that the travel distance from the previous measurement is equal to or greater than the predetermined distance Lkm, the temperature distribution Tθ of one rotation in the circumferential direction of the brake disk 20 is measured in step S203. In the measurement of the temperature distribution Tθ, the temperature is measured by the temperature sensor 50 from both the inside and the outside of the brake disk 20 and is detected in association with the rotation position data from the rotation position sensor 60. Thereby, a temperature distribution Tθ as shown in FIG. 5A can be obtained. As a result, it can be seen that the portion having a high temperature is thick and the portion having a low temperature is thin, and uneven wear can be detected.

  Next, in step S204, based on the detected temperature data, the average temperature T0 for one rotation is calculated by the calculation unit 70b of the brake ECU 70 and recorded in the data storage unit 70a. In step S205, the determination unit 70c determines whether or not the average temperature change per rotation is equal to or greater than the predetermined change amount Tf. The predetermined change amount Tf is a value that is arbitrarily set in order to ensure a certain amount of temperature change because it is difficult to accurately detect uneven wear unless there is a certain amount of temperature change. Note that the average temperature change per rotation is an average obtained by integrating the absolute values of the difference Ta from the average temperature T0, as shown in FIG.

  If it is determined in step S205 that the average temperature change of one rotation is equal to or greater than the predetermined change amount Tf, the detected temperature distribution Tθ of one rotation is recorded in the data storage unit 70a and measured in step S206. The travel distance is recorded in the data storage unit 70a.

  On the other hand, when it is determined in step S205 that the average temperature change of one rotation is less than the predetermined change amount Tf, in step S207, the determination unit 70c determines whether or not the brake is on. If it is determined that the brake is on, the process returns to step S203. By repeating the loop in this manner, it is possible to wait for the average temperature change of one rotation to be equal to or greater than the predetermined change amount Tf and detect minute uneven wear. On the other hand, if it is determined in step S207 that the brake is off, in step S208, it is recorded that correction of the brake disc 20 is unnecessary, and the process is stopped.

  When the temperature distribution Tθ for one rotation is recorded in step S206, the process proceeds to step S209, and the determination unit 70c determines whether or not the temperature change (difference between the maximum temperature and the minimum temperature) Tdif for one rotation is equal to or higher than the predetermined temperature Tx. judge. The predetermined temperature Tx is a temperature change amount obtained in advance in a partial wear state where the brake disk 20 needs to be corrected. If it is determined that the temperature change Tdif for one rotation is equal to or higher than the predetermined temperature Tx, it is recorded in step S210 that the brake disk 20 needs to be corrected, and the process proceeds to a subroutine for correction. On the other hand, if it is determined that the temperature change Tdif of one rotation is less than the predetermined temperature Tx, in step S208, it is recorded that the correction of the brake disk 20 is unnecessary, and the processing is stopped.

  In the correction subroutine, as shown in FIG. 4, first, in step S401, the determination unit 70c determines whether or not the brake is off. If it is determined that the brake is on, the process is stopped. Thus, in this embodiment, correction is performed when the brake is off.

  If it is determined in step S401 that the brake is off, the determination unit 70c determines in step S402 whether the number of corrections from the past is equal to or less than Nset. If it is determined that the number of corrections exceeds Nset, it is recorded in step S403 that correction is not necessary, and the process is stopped.

  On the other hand, if it is determined in step S402 that the number of corrections is Nset or less, a temperature distribution Tθ of one rotation in the circumferential direction of the brake disk 20 is measured in step S404. Next, in step S405, based on the detected temperature data, the average temperature T0 for one rotation is calculated by the calculation unit 70b and recorded in the data storage unit 70a. In step S406, the determination unit 70c determines whether the average temperature for one rotation is equal to or lower than the predetermined temperature Tc1. And when the average temperature of 1 rotation exceeds Tc1, it returns to step S401. This is to prevent the brake disk 20 from being corrected when the temperature is higher than the predetermined temperature Tc1 because the wear characteristic of the brake disk 20 changes depending on the temperature.

  If it is determined in step S406 that the average temperature of one rotation is equal to or less than Tc1, in step S407, a correction hydraulic pressure for correcting uneven wear is calculated by the calculation unit 70b based on the temperature distribution Tθ, and the hydraulic pressure The control unit 70d applies the corrected hydraulic pressure Pr to the brake pad 30 via the wheel cylinder 40. FIGS. 5B and 5C show an example of the correction fluid pressure to be applied. As shown in FIG. 5A, the thickness of the brake disc 20 is thick in the region where the temperature is high, and the thickness is thin in the region where the temperature is low, so the temperature is high as shown in FIGS. 5B and 5C. In the region, the hydraulic pressure is increased and the brake pad 30 is pressed strongly, while in the region where the temperature is low, the hydraulic pressure is decreased and the brake pad 30 is pressed lightly or not pressed. In this way, uneven wear of the brake disc 20 can be corrected. The correction hydraulic pressure Pr is preferably set to a level that does not give the driver a sense of incongruity.

  In step S408, whether or not the brake is on is determined by the determination unit 70c. If it is determined that the brake is off, in step S409, whether the average temperature of one rotation is equal to or lower than the predetermined temperature Tc2. The determination part 70c determines whether or not. If it is determined that the average temperature of one rotation is equal to or lower than the predetermined temperature Tc2, the process returns to step S407 and the load of the correction hydraulic pressure Pr is continued. On the other hand, if it is determined that the average temperature of one rotation exceeds the predetermined temperature Tc2, in step S410, the number of corrections is added once and recorded in the data storage unit 70a, and the process proceeds to step S411. As described above, the wear characteristic of the brake disk 20 changes depending on the temperature. Therefore, if the average temperature of one rotation exceeds the predetermined temperature Tc2, the wear characteristic is greatly fluctuated and the correction process is stopped. It is.

  If it is determined in step S408 that the brake is on, or if the number of corrections is added and recorded in step S410, the load of the correction hydraulic pressure Pr is stopped and the process is stopped in step S411.

  In this way, it is possible to correct the braking torque fluctuation caused by uneven wear of the brake disc 20.

  On the other hand, referring back to FIG. 2 and FIG. 3, if it is determined in step S201 that the brake is off, it is determined in step S211 whether or not it is determined that the brake disk 20 needs to be corrected. It is determined by the unit 70c. If it is determined that there is a need for correction, it is recorded in step S212 that the brake disk 20 needs to be corrected, and the process proceeds to a subroutine for correction.

  If it is determined in step S211 that there is no need for correction, the process proceeds to correction of drag torque fluctuation. In this way, the drag torque fluctuation is corrected when the brake is off.

  In correcting the drag torque fluctuation, first, in step S301, the temperature distribution Tθ of one rotation in the circumferential direction of the brake disk 20 is measured. Next, in step S302, based on the detected temperature data, the average temperature T0 for one rotation is calculated by the calculation unit 70b and recorded in the data storage unit 70a. In step S303, the determination unit 70c determines whether or not the average temperature T0 for one rotation is equal to or lower than the predetermined temperature Tc3. If the average temperature of one rotation exceeds Tc3, the process is stopped. This is because the brake disk 20 is not corrected when the temperature is higher than the predetermined temperature Tc3 because the wear characteristic of the brake disk 20 changes depending on the temperature.

  If it is determined in step S303 that the average temperature T0 for one rotation is equal to or lower than the predetermined temperature Tc3, the temperature distribution Tθ for one rotation of the brake disk 20 is measured again in step S304.

  In step S305, the temperature distribution Tθ of one rotation is integrated and Tθsum is obtained by the calculation unit 70b. Next, in step S306, it is determined by the determination unit 70c whether or not the brake is on. If it is determined that the brake is on, the process is stopped while it is determined that the brake is off. In step S307, the determination unit 70c determines whether or not the number of integrations of the temperature distribution Tθ of one rotation is equal to or greater than Nsum. If it is determined that the number of integrations is less than Nsum, the process returns to step S304. Thus, the temperature distribution Tθ of one rotation is integrated until the number of integration reaches Nsum or more. When the brake drag is detected, the brake pad 30 is not pressed, so the temperature distribution deviation is very small and difficult. However, by integrating the temperature distribution Tθ in this way, the deviation is increased and becomes minute. Detect uneven wear reliably. The cumulative number Nsum is determined in advance as a number sufficient to detect the occurrence of drag torque.

  Then, if it is determined in step S307 that the number of times of integration of the temperature distribution Tθ for one rotation is equal to or greater than Nsum, the temperature change (difference between the maximum temperature and the minimum temperature) Tdif for one rotation is a predetermined change amount in step S308. It is determined by the determination part 70c whether it is more than Td. The predetermined change amount Td is a value obtained in advance corresponding to a partial wear state in which the brake disk 20 needs to be corrected.

  If it is determined that the temperature change Tdif of one rotation is equal to or higher than the predetermined temperature Td, it is recorded in step S309 that the brake disk 20 needs to be corrected, and the process proceeds to a subroutine for correction. On the other hand, if it is determined that the temperature change Tdif of one rotation is lower than the predetermined temperature Td, the process is stopped because it is unnecessary to correct the brake disk 20. The subroutine for correcting the brake disk 20 is the same as that described above. In this way, drag torque fluctuation caused by uneven wear of the brake disc 20 can be corrected.

  As described above in detail, the state of the brake disk 20 tends to appear as a temperature distribution in the circumferential direction. In this embodiment, the surface state can be detected by detecting the temperature distribution Tθ in the circumferential direction of the brake disk 20. Therefore, it is possible to detect a minute uneven wear as compared with the case where the state is detected by measuring the fluctuation of the hydraulic pressure.

  Since the correction hydraulic pressure Pr can be applied to the wheel cylinder 40 based on the detected temperature distribution Tθ, it is possible to correct the braking torque fluctuation caused by uneven wear.

  Further, by integrating the temperature distribution Tθ detected at different times, even if the deviation of the temperature distribution Tθ is small, the deviation can be increased by integrating, so that minute uneven wear can be more reliably performed. It becomes possible to detect. In particular, the detection of brake drag is particularly suitable because the deviation of the temperature distribution Tθ is very small. In this way, it is possible to correct drag torque fluctuations caused by uneven wear of the brake disc 20.

  Further, since the temperature sensor 50 is disposed on both the inner surface side and the outer surface side of the brake disc 20, the surface state of the inner surface side and the outer surface side of the brake disc 20 can be separately detected. It is also possible to specify the surface where the drag is generated.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, the temperature sensor 50 is disposed on both the inner surface side and the outer surface side of the brake disk 20, but may be disposed only on one side.

It is a figure which shows typically the braking device provided with the state detection apparatus of the brake disc which concerns on this embodiment. It is a flowchart which shows the method of correcting the braking torque fluctuation | variation resulting from the uneven wear of a brake disc. It is a flowchart which shows the method of correcting the drag torque fluctuation | variation resulting from the uneven wear of a brake disc. It is a flowchart which shows the subroutine for correcting the braking torque fluctuation | variation and drag torque fluctuation | variation resulting from the uneven wear of a brake disc. (A) is a graph which shows the temperature distribution of the circumferential direction of a brake disc, (b) and (c) are graphs which show an example of the correction | amendment hydraulic pressure applied in order to correct uneven wear.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Brake device, 20 ... Brake disk, 30 ... Brake pad (friction material), 40 ... Wheel cylinder, 50 ... Temperature sensor (temperature distribution detection means), 60 ... Rotation position sensor (temperature distribution detection means), 70 ... Brake ECU, 70a ... data storage unit, 70b ... calculation unit (integration means), 70c ... determination unit, 70d ... hydraulic pressure control unit, 80 ... brake pedal.

Claims (3)

A brake disk state detection device for braking the rotation of a wheel by pressing a friction material on the surface,
A brake disk state detection device comprising temperature distribution detection means for detecting a temperature distribution in a circumferential direction of the brake disk.   2. The brake disk state detection device according to claim 1, wherein the temperature distribution detection unit includes an integration unit that integrates the temperature distributions detected at different times. 3. The brake disk state detection device according to claim 1 or 2, wherein the temperature distribution detection means includes a temperature sensor, and the temperature sensor is arranged on both the inner surface side and the outer surface side of the brake disk. .

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