JP2006161899A - Braking device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking device for easily and accurately finding the wear amount of a friction member. <P>SOLUTION: The braking device comprises a zero piston position storage part 25 for storing a piston position in a motor cylinder 7 when replacing a brake pad with new one and a braking pressure sensor 23 for detecting hydraulic pressure generated between the motor cylinder 7 and a brake caliper 4 in a sealed condition. The wear amount of the brake pad is calculated in accordance with a relationship between a piston stroke from a zero piston position stored by the zero piston position storage part 25 and the hydraulic pressure detected by the braking pressure sensor 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hydraulic braking device that makes it easy to detect the amount of wear of a braking member.

2. Description of the Related Art Conventionally, a vehicle braking device has a hydraulic cylinder that generates a hydraulic pressure by being electrically operated in response to the braking operation, in addition to a master cylinder that is mechanically operated in response to a braking operation by a driver. There is one configured as a so-called brake-by-wire that generates a braking pressure in a wheel cylinder by a hydraulic pressure generated by the hydraulic cylinder (see, for example, Patent Document 1).
By the way, in a vehicle braking device, in order to inform the driver that the braking member in the wheel cylinder is at the time of replacement, for example, the braking member has been subjected to predetermined processing, and the braking member has reached the wear limit. Has a built-in wear sensor capable of electrically detecting (see, for example, Patent Document 2).
Japanese National Publication No. 9-511967 JP-A-5-248464

However, in the configuration for detecting the frictional state of the braking member, there is a problem in that the friction member needs to be subjected to predetermined processing, resulting in an increase in cost due to an increase in the number of manufacturing steps.
Further, as a configuration having the same action as described above, for example, a friction plate is attached with a metal plate on which a wear sensor is formed, and a contact sound between the wear sensor and the braked member informs that the brake member has reached the wear limit. However, in this configuration, there is a problem that the contact sound between the friction sensor and the member to be braked may cause the driver to feel uncomfortable or the driver may not be aware of the meaning of the contact sound.

Furthermore, without using the above wear sensors, the working fluid in the reservoir tank decreases as the friction material wear increases, so the friction material wear status can be determined by checking the fluid volume in the reservoir tank. However, there is a problem that such a determination is difficult unless the driver understands the structure of the braking device.
Therefore, the present invention does not require the generation of contact noise between the friction sensor wear sensor and the non-braking member, and does not require special processing on the braking member, so that the wear amount of the friction member can be known easily and reliably. A braking device that can be used is provided.

  As a means for solving the above-mentioned problems, the invention described in claim 1 includes a hydraulic cylinder (for example, the motor cylinder 7 of the embodiment) that generates hydraulic pressure in response to a driver's braking operation, and the hydraulic cylinder generates. A wheel cylinder (for example, the brake caliper 4 of the embodiment) that generates a braking pressure by a hydraulic pressure, and a braking member (for example, the brake disc 4a of the embodiment) that is connected to the wheel cylinder and generates a braking force. For example, the brake pad 17) of the embodiment, the zero piston position storage means (for example, the zero piston position storage section 25 of the embodiment) for storing the piston position of the hydraulic cylinder when the brake member is newly replaced, Fluid pressure detecting means for detecting the fluid pressure generated between the fluid pressure cylinder and the wheel cylinder in a sealed state (for example, the braking pressure sensor 23 of the embodiment) In the braking device (for example, the braking device 1 of the embodiment), the relationship between the piston movement amount from the piston position stored by the zero piston position storage unit and the hydraulic pressure detected by the hydraulic pressure detection unit, The amount of wear of the braking member is calculated.

  According to this configuration, the piston position (zero piston position) of the hydraulic cylinder at the time of non-braking operation when the brake member is newly replaced (when the hydraulic pressure of the wheel cylinder becomes 0) is stored, while the braking member The piston position of the hydraulic cylinder at the time of non-braking operation is monitored even after the start of use of the cylinder. Based on the difference (piston movement amount) between these zero piston position and the latest piston position, the piston position of the wheel cylinder and the braking member The amount of wear and the like can be calculated.

  According to the second aspect of the present invention, a hydraulic cylinder (for example, the sub-cylinder 107 in the embodiment) that generates a hydraulic pressure in response to a driver's braking operation, and a braking pressure is generated by the hydraulic pressure generated by the hydraulic cylinder. A wheel cylinder (for example, the brake caliper 4 of the embodiment), and a braking member (for example, the brake pad 17 of the embodiment) that is connected to the wheel cylinder and generates a braking force on the braked member (for example, the brake disk 4a of the embodiment). ) In a state where the hydraulic cylinder and the wheel cylinder are hermetically sealed, depending on the piston position of the hydraulic cylinder during non-braking operation. The amount of wear of the member is calculated.

  According to this configuration, since the space between the hydraulic cylinder and the wheel cylinder is hermetically sealed, the wheel cylinder is monitored based on the piston position by monitoring the piston position of the hydraulic cylinder during non-braking operation. It is possible to calculate the piston position and the wear amount of the braking member.

  According to the first and second aspects of the present invention, the wear amount of the braking member and the like can be calculated based on the piston position of the hydraulic cylinder that is sealed with the wheel cylinder. This eliminates the need to generate a contact sound between the friction sensor wear sensor and the non-braking member or to perform special processing on the braking member, as in the past. And the wear amount of a friction member can be known reliably. In particular, it can be said that it is suitable for an existing configuration configured as a brake-by-wire having a hydraulic cylinder different from the master cylinder.

Embodiments of the present invention will be described below with reference to the drawings.
In the braking device 1 shown in FIG. 1, reference numeral 2 denotes a tandem master cylinder that generates hydraulic pressure (hydraulic pressure) in response to a braking operation to the brake pedal 3 by the driver. Each hydraulic pressure chamber 5 of the master cylinder 2 is connected to a hydraulic pressure path 5 leading to a brake caliper (wheel cylinder) 4 that generates braking pressure to each wheel. A shut-off valve 6 that is electrically operated to switch between shut-off or open is provided at an intermediate portion of each hydraulic pressure path 5, and at a position closer to the brake caliper 4 than the shut-off valve 6 in each hydraulic pressure path 5. Are separately provided with motor cylinders (hydraulic cylinders) 7 that are electrically operated to generate hydraulic pressure separately from the master cylinder 2. Hereinafter, the upstream side (master cylinder 2 side) of the hydraulic path 5 with respect to the shutoff valve 6 is referred to as a first hydraulic path 5a, and the downstream side (brake caliper 4 side) is referred to as a second hydraulic path 5b.

  Each shut-off valve 6 is a solenoid valve configured to shut off the hydraulic pressure path 5 when energized to its own solenoid and open the hydraulic pressure path 5 by the biasing force of its own coil spring when not energized. Further, each motor cylinder 7 transmits the driving force of the drive motor 11 capable of forward / reverse rotation to the hydraulic pressure generator 13 via the speed reduction mechanism 12, and increases or decreases the hydraulic pressure in the hydraulic pressure generator 13. The corresponding brake caliper 4 generates braking pressure or releases the braking pressure.

  The brake device 1 is configured as a so-called brake-by-wire in which each shut-off valve 6 shuts off the hydraulic pressure path 5 during normal operation and generates a brake pressure on each brake caliper 4 by the hydraulic pressure from each motor cylinder 7. For example, at the time of electrical failure, each shutoff valve 6 opens the hydraulic pressure path 5, and it is possible to generate braking pressure directly on each brake caliper 4 without electrical control by the hydraulic pressure from the master cylinder 2. Is done. In FIG. 1, a thick line indicates a hydraulic pipe, and a thin line indicates a telecommunication line. In the figure, reference numeral 4a denotes a brake disk (a member to be braked) that rotates integrally with the wheel, reference numeral 2a denotes a reservoir tank of hydraulic fluid in the master cylinder 2, and reference numeral 8 denotes operational feeling of the brake pedal 3 during normal operation. Each of the pedal simulators for providing

  Each shut-off valve 6 and motor cylinder 7 are driven and controlled by an ECU (Electronic Control Unit) 21. The ECU 21 detects the detected value from the operation pressure sensor 22 that detects the hydraulic pressure (operating pressure) in each first hydraulic pressure passage 5a, and the hydraulic pressure (braking pressure) in each second hydraulic pressure passage 5b. A detection value from the braking pressure sensor 23, an ON / OFF signal from the brake switch 24, and the like are input.

  As shown in FIG. 2, the motor cylinder 7 includes, for example, a drive motor 11 as a servo motor connected in series to a cylinder (hereinafter referred to as a motor side cylinder) 14 of a hydraulic pressure generator 13, and a drive shaft of the drive motor 11. Is converted into a linear motion of a piston (hereinafter referred to as motor-side piston) 15 in the motor-side cylinder 14 via a speed reduction mechanism 12 as a ball screw mechanism, and reciprocated so that the inside of the motor-side cylinder 14 Increase or decrease the hydraulic pressure. In the figure, reference numeral 14a denotes an air vent valve in the motor side cylinder 14.

  On the other hand, as shown in FIG. 3, the brake caliper 4 is provided on both sides of the caliper body 16 that is provided so as to straddle the brake disc 4a from the outside in the radial direction and is supported on the vehicle body side, and to sandwich the brake disc 4a. A pair of brake pads (braking members) 17 disposed and supported by the caliper main body 16 and fitted in a caliper cylinder 18 formed on the caliper main body 16 provided on one brake pad 17 opposite to the brake disc 4a. And a caliper piston 19 to be mounted.

  The brake pad 17 is formed, for example, by integrally forming a layer of a non-asbestos friction material 17b on a metal base plate 17a. The base plate 17a is frictionally applied to the caliper piston 19 side or the caliper body 16 side. The material 17b is assembled to the caliper main body 16 in a state where the material 17b is arranged facing the brake disc 4a side.

The caliper cylinders 18 communicate with the motor side cylinders 14 of the corresponding motor cylinders 7 via the second hydraulic pressure passages 5b. When a braking operation is performed by the driver, each motor cylinder 7 is driven to rotate forward. A hydraulic pressure is supplied into the caliper cylinder 18, and the caliper piston 19 is moved in a direction in which the caliper piston 19 is pushed out from the caliper cylinder 18 (hereinafter referred to as a piston push-out direction). While pressing against the side surface, the caliper body 16 is slid by the reaction force and the other brake pad 17 is pressed against the other side surface of the brake disc 4a.
As a result, the brake caliper 4 presses each brake pad 17 against the brake disk 4a so that it is clamped (clamped). The friction between each brake pad 17 and the brake disk 4a causes the rotation of the brake disk 4a and the wheel. Is braked.

  On the other hand, when the braking operation by the driver is finished, each motor cylinder 7 is reversely driven until the hydraulic pressure in the corresponding caliper cylinder 18 (in other words, the clamping force to the brake disc 4a by the brake caliper 4) becomes zero, Clamping of the brake disc 4a by the brake caliper 4 is released, and the brake disc 4a and thus the wheels return to a rotatable state. The reverse rotation of the motor cylinder 7 at this time is stopped when the detected value of the braking pressure sensor 23 is used as the hydraulic pressure in the caliper cylinder 18 and becomes zero. At this time, the brake pads 17 return from the pressed state to the brake disk 4a to the state before the press due to the lowering of the hydraulic pressure in the caliper cylinder 18 and the return action of the piston seal (not shown).

  Here, when the position of the motor-side piston 15 relative to the motor-side cylinder 14 at the time of non-braking operation (when the hydraulic pressure of the brake caliper 4 becomes 0) is the piston position A0, each brake pad 17 is newly replaced ( The piston position A0 when the brake pad 17 starts to be worn and worn (when the brake pad is worn) with respect to the piston position A0 (hereinafter referred to as zero piston position A0max) of the new brake pad) It will change in the piston pushing direction. The piston position A0 when the brake pad 17 is worn is based on the zero piston position A0max and takes into account the rotor rotation angle detected by a resolver (not shown) mounted on the drive motor 11 and the speed reduction ratio of the speed reduction mechanism 12. And can be calculated. Hereinafter, the difference between the zero piston position A0max and the piston position A0 when the brake pad is worn is referred to as a motor side piston stroke amount Scyl.

  The motor cylinder 7 (motor side cylinder 14) and the brake caliper 4 (caliper cylinder 18) are connected in a sealed state without interposing a reservoir tank or the like via the second hydraulic pressure path 5b. Based on the amount Scyl, the position of the caliper piston 19 relative to the caliper cylinder 18 when the brake pad is new and the wear of the brake pad are calculated by calculating the ratio of the diameter of the motor side piston 15 and the diameter of the caliper piston 19. The difference between the position of the caliper piston 19 relative to the caliper cylinder 18 (hereinafter referred to as the caliper piston stroke amount Scal) can be calculated, and the wear amount of the brake pad 17 can be directly known from the caliper piston stroke amount Scal. Obtainable.

  That is, with reference to FIG. 1 as well, in the ECU 21, the zero piston position storage unit 25 stores the zero piston position A0max, while the piston position calculation unit 26 calculates the latest piston position A0 and the wear amount. The calculation unit 27 calculates the wear amount of the brake pad 17 by performing a calculation using a predetermined coefficient based on the difference (motor-side piston stroke amount Scyl) between the zero piston position A0max and the latest piston position A0. It has become. Further, since the brake pad 17 is usually sized in accordance with the brake caliper 4, the remaining wear of the brake pad 17 is considered by considering the thickness T 0 of the friction material 17 b when the brake pad is new. It is also possible to know the quantity Tp.

FIG. 4 shows a change in hydraulic pressure during braking operation in each wear state of the brake pad 17 when the vertical axis is the hydraulic pressure P detected by the braking pressure sensor 23 and the horizontal axis is the motor side piston stroke amount Scyl. It is a graph.
As shown in the figure, the starting point of the hydraulic pressure change curve in each wear state, that is, the piston position A0 in the hydraulic pressure P = 0 state increases the motor-side piston stroke amount Scyl as the wear amount of the brake pad 17 increases. Change direction. The hydraulic pressure change curve in each wear state rises from each piston position A0 so as to have substantially the same characteristics.

  Each piston position A0 is monitored by the ECU 21, and the wear remaining amount (hereinafter referred to as pad remaining amount) Tp of the brake pad 17 calculated based on each piston position A0 is used as a predetermined display unit 28 (see FIG. 1). This is displayed to inform the driver of this. When the motor-side piston 15 reaches a position corresponding to a state where the brake pad 17 has reached the wear limit (hereinafter referred to as a limit piston position) A0min, the brake pad 17 is at the replacement time together with the remaining pad amount Tp. A predetermined warning display for informing the driver of this is performed.

Next, a processing procedure in the ECU 21 when the braking device 1 calculates the wear amount of the brake pad 17 and displays the remaining pad amount Tp and the like will be described based on the flowchart shown in FIG.
First, when the ignition is turned ON, the detection of the piston position A0 in the zero hydraulic state is continuously performed (step S1), and the latest piston position A0n + 1 is detected before that. On the other hand, it is determined whether or not the direction has changed in the piston push-back direction (the direction opposite to the piston push-out direction) (step S2).

  At this time, if it is determined that the latest piston position A0n + 1 has changed in the piston push-back direction with respect to the previous piston position A0n (YES), it is determined that the brake pad 17 has been replaced. The piston position A0n + 1 is stored in place of the already stored zero piston position A0max (step S3).

  If it is determined in step S2 that the latest piston position A0n + 1 has changed in the same position or in the pushing direction with respect to the previous piston position A0n (NO), or after the processing in step S3, In S4, a motor side piston stroke amount Scyl as a difference between the stored zero piston position A0max and piston position A0 is calculated, and in step S5, the pad of the brake pad 17 is calculated based on the motor side piston stroke amount Scyl. The remaining amount Tp is calculated.

  Next, it is determined whether or not the calculated pad remaining amount Tp is equal to or greater than a predetermined value, in other words, whether or not the brake pad 17 has reached the wear limit (step S6). Specifically, it is determined whether or not the piston position A0 has reached the limit piston position A0min. At this time, if it is determined that the remaining pad amount Tp is less than the predetermined value (NO), a warning display indicating that the brake pad 17 is in the replacement period is displayed on the display unit 28 together with the display of the remaining pad amount Tp. When it is determined that the value is equal to or greater than the predetermined value (YES), the display unit 28 is caused to display only the remaining pad amount Tp (step S8).

  As described above, the braking device 1 in the above embodiment includes the motor cylinder 7 that generates hydraulic pressure in response to the driver's braking operation, and the brake caliper that generates braking pressure by the hydraulic pressure generated by the motor cylinder 7. 4, a brake pad 17 that is connected to the brake caliper 4 and generates a braking force on the brake disc 4a, and a zero piston position in the ECU 21 that stores the piston position of the motor cylinder 7 when the brake pad 17 is newly replaced A storage unit 25 and a braking pressure sensor 23 for detecting a hydraulic pressure generated between the motor cylinder 7 and the brake caliper 4 in a sealed state are provided, and the zero piston position storage unit 25 is provided. Between the piston stroke amount from the zero piston position memorized by the hydraulic pressure detected by the braking pressure sensor 23 More, and calculates the wear amount of the brake pad 17.

  According to this configuration, the piston position (zero piston position) of the motor cylinder 7 at the time of non-braking operation when the brake pad 17 is newly replaced (when the hydraulic pressure of the brake caliper 4 becomes 0) is stored. Even after the start of use of the brake pad 17, the piston position of the motor cylinder 7 during non-braking operation is monitored, and the piston position of the brake caliper 4 is based on the difference (piston stroke amount) between these zero piston position and the latest piston position. As a result, the wear amount of the brake pad 17 can be calculated.

  That is, since the wear amount of the brake pad 17 and the like can be calculated based on the piston position of the motor cylinder 7 that is sealed with the brake caliper 4, this can be displayed on the display unit 28 or the replacement time can be displayed. By performing a warning display for prompting, it is not necessary to generate a contact sound between the wear sensor of the brake pad 17 and the brake disk 4a or to perform special processing on the brake pad 17 as in the prior art. The amount of wear of the brake pad 17 can be known. In particular, it can be said that it is suitable for the braking device 1 configured as a brake-by-wire having a motor cylinder 7 different from the master cylinder 2 as an existing configuration.

  The present invention is not limited to the above-described embodiment. For example, each hydraulic pressure path 5 led out from each hydraulic pressure chamber of the master cylinder 2 toward the brake caliper 4 like a braking device 101 shown in FIG. A sub-cylinder (hydraulic cylinder) 107 is provided in the middle portion of the cylinder, and exhibits a form as a double-acting cylinder that generates hydraulic pressure in response to a driver's braking operation by receiving hydraulic pressure from the master cylinder 2. The cylinder 107 and the brake caliper 4 are connected in a sealed state, and the piston position of the sub cylinder 107 during non-braking operation is detected by a sensor 123, and the wear amount of the brake pad 17 is calculated based on the piston position. May be. In addition, the same code | symbol is attached | subjected to the structure corresponded to the said Example, and the description is abbreviate | omitted.

According to this configuration, since the space between the sub cylinder 107 and the brake caliper 4 is in a sealed state, by monitoring the piston position of the sub cylinder 107 during the non-braking operation, the brake is based on the piston position. Since it is possible to calculate the piston position of the caliper 4 and thus the wear amount of the brake pad 17, it is possible to obtain the same operational effects as in the above embodiment.
The configuration in the above embodiment is an example of the present invention, and various modifications can be made without departing from the gist of the present invention, such as application to a hydraulic drum brake instead of a hydraulic disc brake. Not too long.

BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing of the braking device in the Example of this invention. It is composition explanatory drawing of the motor cylinder of the said braking device. It is explanatory drawing which performed the comparison for every structure of the brake caliper of the said braking device, and brake pad abrasion state. It is a graph in which the vertical axis represents the hydraulic pressure detected by the braking pressure sensor and the horizontal axis represents the piston position of the motor side piston. It is a flowchart which shows the process sequence in ECU at the time of calculating the abrasion amount of a brake pad and displaying a pad residual quantity. It is composition explanatory drawing which shows the modification of the said braking device.

Explanation of symbols

1,101 Braking device 7 Motor cylinder (hydraulic cylinder)
4 Brake caliper (wheel cylinder)
4a Brake disc (braking member)
17 Brake pads (braking members)
23 Braking pressure sensor (hydraulic pressure detecting means)
25 Zero piston position storage unit (zero piston position storage means)
107 Sub cylinder (hydraulic cylinder)

Claims (2)

A hydraulic cylinder that generates hydraulic pressure in response to a driver's braking operation, a wheel cylinder that generates a braking pressure by the hydraulic pressure generated by the hydraulic cylinder, and a braking force that is connected to the wheel cylinder to a braked member In a state where the hydraulic cylinder and the wheel cylinder are hermetically sealed, the brake member for generating the pressure, the zero piston position storage means for storing the piston position of the hydraulic cylinder when the brake member is newly replaced, and the hydraulic cylinder and the wheel cylinder In a braking device comprising a hydraulic pressure detecting means for detecting hydraulic pressure generated during
A braking device characterized in that the amount of wear of the braking member is calculated based on the relationship between the piston movement amount from the piston position stored by the zero piston position storage means and the hydraulic pressure detected by the hydraulic pressure detection means. A hydraulic cylinder that generates a hydraulic pressure in response to a driver's braking operation, a wheel cylinder that generates a braking pressure by the hydraulic pressure generated by the hydraulic cylinder, and a braking force that is connected to the wheel cylinder to a braked member A braking device including a braking member for generating
A braking device that calculates an amount of wear of the braking member based on a piston position of the hydraulic cylinder during a non-braking operation in a state where the hydraulic cylinder and the wheel cylinder are sealed.

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