JP5234266B2 - Disc brake device - Google Patents

Description

  The present invention relates to a disc brake device for a vehicle provided with a parking brake mechanism.

2. Description of the Related Art Conventionally, as a hydraulic disc brake mounted on a vehicle such as an automobile, a parking brake is operated by an electric motor as described in Patent Document 1, for example. In the device described in Patent Document 1, the operation state of the parking brake is stored in a non-volatile memory (EEPROM), so that when the vehicle ignition switch is turned off, the vehicle is reliably turned on. The parking brake control can be continued.
JP 2007-216896 A

  However, in the case where the operation state of the parking brake is stored in the nonvolatile memory as described in Patent Document 1, there is the following problem. If the data stored in the non-volatile memory is lost due to some cause such as an electric shock, normal parking brake control cannot be performed. Also, under certain circumstances, for example, when the parking brake is manually released with the ignition switch turned off for vehicle maintenance after the parking brake is activated, the nonvolatile memory is turned on when the ignition switch is turned on. However, although the parking brake operation state is stored, the parking brake may actually be released, which causes a problem in controlling the parking brake.

  An object of this invention is to provide the disc brake apparatus which can determine the actual operating state of a parking brake.

In order to solve the above problems, the present invention is mounted to the caliper for pressing the slidably provided a piston with a pair of brake pads disposed on both sides of the disk rotor of the vehicle into the cylinder, before a screw mechanism for fixing the piston at a braking position in contact with the Kipi piston, a parking brake mechanism having a drive mechanism for actuating the screw mechanism by an electric motor,
In the disc brake system and a control means for controlling said electric motor,
The control means includes
Supplying a predetermined drive current to the electric motor to monitor the rotation of the electric motor;
When the electric motor rotates, it is determined that the parking brake is released,
When the electric motor does not rotate, it has a parking brake operation / release determination processing unit that determines that the parking brake is operating.
The parking brake operation / release determination processing unit performs the determination process at a predetermined timing from when the ignition switch of the vehicle is turned off to when it is turned on .

  The disc brake device according to the present invention can determine the actual operating state of the parking brake.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of a vehicle to which the disc brake device according to this embodiment is applied. With reference to FIG. 1, the structure of the disc brake apparatus 1 which concerns on this embodiment is demonstrated. A hydraulic disc brake 3 is mounted on the front wheel 2, and a hydraulic disc brake 5 including a parking brake mechanism 5 </ b> A is mounted on the rear wheel 4. A hydraulic pressure control section 6 for controlling the hydraulic pressure supplied to the hydraulic brake lines of the disc brakes 3, 5 of each wheel is connected.

  The hydraulic pressure control unit 6 includes a brake sensor 8 that detects an operation (pedal stroke, pedal effort, etc.) of the brake pedal 7 by the driver, and hydraulic pressure sensors 9 and 10 that detect the hydraulic pressures of the disc brakes 3 and 5. It is connected. The hydraulic pressure control unit 6 includes various sensors such as a door switch 11 for detecting the open / closed state of the vehicle door, a key lock 12 for detecting the unlocked state, a key switch 12 for detecting the vehicle state, and an engine controller. In-vehicle equipment is connected. These connections and transmission of various signals described below can be established by, for example, a known in-vehicle network (CAN).

  Then, according to the brake operation by the driver, the hydraulic pressure control unit 6 supplies hydraulic pressure to the disc brakes 3 and 5 to generate a braking force. Further, based on vehicle information detected by various sensors and vehicle-mounted devices, the hydraulic pressure control unit 6 controls the hydraulic pressure supplied to the disc brakes 3 and 5 to thereby provide boost control, braking force distribution control, and brake assist control. Brake control such as anti-lock control, traction control, vehicle stabilization control, and slope start assist control can be executed.

  Further, the disc brake device 1 is provided with a parking brake controller 13 (control means). The parking brake controller 13 is connected to the parking brake switch 14 and the hydraulic pressure control unit 6, and the parking brake mechanism 5A is incorporated based on the operation of the parking brake switch 14 by the driver and information from various sensors and in-vehicle devices. The control signal is output to the disc brake 5 and the hydraulic pressure control unit 6 to control the operation of the parking brake.

Next, the structure of the disc brake 5 in which the parking brake mechanism 5A is incorporated will be described with reference to FIGS.
As shown in FIG. 3, the disc brake 5 is a caliper floating type hydraulic disc brake, and includes a pair of brake pads 16 disposed on both sides of a disc rotor 15 that rotates together with the wheels 4 (see FIG. 1), a disc A caliper 17 that straddles the rotor 2 and a carrier (not shown) that is fixed to a non-rotating portion of the vehicle and supports the brake pad 16 and the caliper 17 so as to be movable along the axial direction of the disk rotor 2 are provided.

  The caliper 17 is provided with a cylinder 18 at a portion facing one brake pad 16, and a claw portion 17 </ b> A facing the other brake pad 16 is formed across the disk rotor 2. A cylindrical piston 19 with a bottom is inserted into the cylinder 18, and the hydraulic pressure is supplied from the hydraulic pressure control unit 6 to the cylinder 18 to advance the piston 19 and press the brake pad 16 against the disc rotor 15. To generate a braking force.

The parking brake mechanism 5A incorporated in the disc brake 5 will be described.
A lock nut 20 is slidably inserted into the piston 19, and an outer flange portion 21 formed at the rear end portion of the lock nut 20 is in contact with the rear end portion of the piston 19. The lock nut 20 is prevented from rotating by inserting an axially extending pin 22 attached to the flange portion 21 into the side wall of the piston 19. Further, the piston 19 is prevented from rotating with respect to the caliper 17. The lock nut 20 is screwed with the leading end of the feed screw 23, and the lock nut 20 and the feed screw 23 constitute a screw mechanism for fixing the piston 19 at the braking position . The rear end portion of the feed screw 23 is inserted and penetrated through the bottom portion of the cylinder 18 in a liquid-tight and rotatable manner, and extends to the inside of the drive mechanism 24 attached to the rear end portion of the caliper 17. The feed screw 23 is supported on the bottom portion of the cylinder 18 by a flange portion 25, a thrust bearing 26 and a fixing nut 27 formed at an intermediate portion thereof, and is fixed in the axial direction.

  The drive mechanism 24 is a combination of an electric motor 28 (hereinafter referred to as the motor 28) and a speed reduction mechanism including a worm 30 attached to a shaft 29 of the motor 28 and a worm wheel 31 engaged with the worm 30. The worm wheel 31 is connected to the rear end portion of the feed screw 23 extended from the cylinder 18. Thereby, the rotation of the motor 28 can be decelerated to drive the feed screw 23, and the lock nut 20 can be moved forward or backward by the rotation of the feed screw 23. Further, when the motor 28 is stopped, the rotation of the feed screw 23 can be locked by the engagement of the worm 30 and the worm wheel 31.

  The lock nut 20 can move independently by moving the flange portion 21 away from the piston 19 when the flange portion 21 moves forward, while the flange portion 21 presses the piston 19 and moves the piston 19 forward when moving forward. When the piston 19 is advanced by hydraulic pressure, the flange portion 21 is separated from the piston 19 so that the piston 19 can be advanced alone.

  As shown in FIG. 4, the screw portion 20A of the lock nut 20 and the screw portion 23A of the feed screw 23 which are screwed together are trapezoidal screws having a certain play δ in the axial direction, and are non-reciprocal screws. When an axial load is applied between the lock nut 20 and the feed screw 23, the rotation is locked by the frictional force, and the movement in the axial direction is fixed. 4A shows a state in which the lock nut 20 is displaced in the forward direction with respect to the feed screw 23, and FIG. 4B shows a state in which the lock nut 20 is displaced in the backward direction with respect to the feed screw 23. Indicates the state.

Next, the operation of the parking brake will be described.
When operating the parking brake, the parking brake controller 13 outputs a control signal to the hydraulic pressure control unit 6 and the motor 28 of the disc brake 5 by turning on the parking brake switch 14, and the hydraulic pressure to the cylinder 18. And the feed screw 23 is rotated by operating the motor 28. As a result, the piston 19 and the lock nut 20 move together to press the brake pad 16 against the disc rotor 15 to generate a braking force. Thereafter, the hydraulic pressure to the cylinder 18 is released and the motor 28 is stopped. At this time, the frictional force between the screw portion 23A of the feed screw 23 and the screw portion 20A of the lock nut 20 and the worm 30 and the worm wheel 31 against the reaction force of the pressing force of the brake pad 16 to the disc rotor 15 , The rotation of the feed screw 23 is locked and the lock nut 20 is fixed in the axial direction. Thereby, even if the hydraulic pressure to the cylinder 18 is released and the energization to the motor 28 is stopped, the piston 19 can be held at the braking position, and the braking force as a parking brake can be held.

  When releasing the parking brake, the parking brake controller 13 outputs a control signal to the hydraulic pressure control unit 6 and the motor 28 of the disc brake 5 by turning off the parking brake switch 14, and the hydraulic pressure to the cylinder 18. And the motor 28 is rotated in the direction opposite to that when the parking brake is operated. At this time, the thrust of the piston 19 increases due to the increase in the hydraulic pressure of the cylinder 18, thereby releasing the lock due to the frictional force between the screw portions 20 </ b> A and 23 </ b> A. As a result, the feed screw 23 rotates in the direction opposite to that when the parking brake is operated, and the lock nut 20 moves backward. Thereafter, by releasing the hydraulic pressure in the cylinder 18, the piston 19 moves backward, and the parking brake is released.

  Next, a parking brake operation / release determination process for determining whether the parking brake is actually in an activated state or a released state by the parking brake controller 13 will be described with reference to FIGS. explain. As shown in FIG. 2, the parking brake controller 13 is provided with a parking brake operation / release determination processing unit 32. The parking brake operation / release determination processing unit 32 includes a determination availability determination processing unit 33 that determines whether the parking brake operation / release determination process can be executed, and a motor drive unit 34 that outputs a drive signal to the motor 28 of the disc brake 5. And a motor rotation presence / absence determination processing unit 35 for detecting the presence / absence of rotation of the motor 28.

  The parking brake controller 13 executes a parking brake operation / release determination process at a predetermined timing. For example, when the door key is detected to be unlocked by the key switch 12, the door switch 11 is detected to open the door, or the ignition switch is turned on, for example, at certain time intervals when the vehicle is stopped Etc. can be set.

The parking brake operation / release determination processing routine will be described with reference to the flowchart of FIG. When the parking brake operation / release determination process is executed, the determination availability determination processing unit 33 determines whether the parking brake operation / release determination process can be executed based on the vehicle state (step S1). For example, when a predetermined vehicle state that is not suitable for execution of the parking brake operation / release determination process is detected, such as when the vehicle is running or braking by the brake pedal 7, the parking brake operation / release determination is not possible. (Step S2), the parking brake operation / release determination process is terminated.

When a predetermined vehicle state that is not suitable for execution of the parking brake operation / release determination process is not detected, the motor drive unit 34 moves the motor 28 forward in the lock nut 20 (that is, the direction in which the piston 19 presses the brake pad 16). ) Is supplied with a predetermined drive current for a predetermined time (step S3). Then, the rotation of the motor 28 is monitored by the motor rotation presence / absence determination processing unit 35 (step S4). When the rotation of the motor 28 is not detected, a frictional force is generated between the lock nut 20 and the screw portions 20A of the feed screw 23 by the reaction force of the brake pad 16 being pressed against the disk rotor 15, and the feed screw 23 is rotated. It is determined that the vehicle is locked, that is, the parking brake is operating (step S5), and this routine is terminated.
In the state where the friction force is generated between the screw portions 20A and 23A and the rotation of the feed screw 23 is locked, the motor 28 does not rotate in any direction. Therefore, the driving direction of the motor 28 is as described above. The reverse direction, that is, the direction in which the lock nut 20 is retracted may be used.

  When the rotation of the motor 28 is detected, no frictional force is generated between the lock nut 20 and the screw portions 20A and 23A of the feed screw 23, and the rotation of the feed screw 23 is not locked. Then, it is determined that the release state is established (step S6), and then the motor 28 is rotated in the reverse direction to return the feed screw 23 to the initial position (step S7), and this routine is terminated.

  In this way, by supplying a predetermined drive current to the motor 28 and monitoring the presence or absence of the rotation, it is possible to reliably determine whether the parking brake is actually in the operating state or in the released state. .

Next, determination of the presence / absence of rotation of the motor 28 by the motor rotation presence / absence determination processing unit 35 will be described with reference to FIGS.
A drive current is supplied to the motor 28 by the motor drive unit 34 and the current value is monitored to detect the rotation of the motor 28. When the motor 28 rotates, as shown in FIG. 5, when a drive current is supplied to the motor 28 at the time T2 from the motor stop state at the time T1, the current value is after the start-up current (stall current) is generated. It decreases with the rotation of the motor 28. Therefore, the rotation of the motor 28 can be determined by comparing the current value with a predetermined threshold value to detect a decrease in current. Thereafter, a reverse drive current is supplied to the motor 28 at time T3, the rotational position of the motor 28 is returned to the initial position, and the motor 28 is stopped at time T4.

  When the motor 28 does not rotate, as shown in FIG. 6, when a drive current is supplied to the motor 28 at time t2 from the motor stop state at time t1, a starting current (stall current) is generated, and the current value is Since the motor 28 does not rotate, it is maintained constant. Therefore, it is possible to determine that the motor 28 does not rotate by comparing the current value with a predetermined threshold value and detecting that the current does not decrease for a certain period of time. Thereafter, the motor 28 is stopped at time t3.

  Here, since the stall current varies depending on the power supply voltage, the coil temperature of the motor 28, and the like, the current threshold of the motor 28 is determined to be a constant value in consideration of these conditions, or according to these conditions. It is preferable that accurate determination can be made by changing the value. Further, instead of comparing the current of the motor 28 with a threshold value, the rotation rate of the motor 28 is detected by monitoring the rate of change of the current and the waveform (presence / absence of current ripple, etc.), or using the rotation sensor. You may make it detect directly the rotation of.

Even when the parking brake is in operation, if the hydraulic pressure is supplied to the cylinder 18 of the disc brake 5 due to the driver's operation of the brake pedal 7 or the like and the thrust is generated in the piston 19, this causes the lock. Since the frictional force between the nut 20 and the threaded portions 20A and 23B of the feed screw 23 decreases, there is a possibility that when the drive current is supplied to the motor 28, the motor 28 rotates by overcoming the lock of the rotation of the feed screw 23. is there. Therefore, when it is detected by the hydraulic sensor 10 that the hydraulic pressure in the cylinder 18 has reached a predetermined value, or when an operation of the brake pedal 7 is detected by the brake sensor 8, the determination availability determination processing unit 33 performs the determination. The parking brake operation / release determination process may be stopped.
Further, in the present embodiment, it has been described that the present invention is applied to the one that supplies hydraulic pressure to the cylinder 18 when the parking brake is operated / released. The present invention may be applied to a configuration in which the piston 19 is advanced and retracted only by the electric motor 28 without supplying the hydraulic pressure to 18.

1 is a diagram showing a schematic configuration of a vehicle to which a disc brake device according to an embodiment of the present invention is applied. It is a block diagram which shows schematic structure of the parking brake action | operation / release determination process part of the disc brake apparatus which concerns on one Embodiment of this invention. It is a longitudinal cross-sectional view of the disc brake incorporating the parking brake mechanism with which the vehicle shown in FIG. 1 was mounted | worn. FIG. 4 is an enlarged vertical cross-sectional view illustrating a threaded portion of a lock nut and a feed screw of the disc brake illustrated in FIG. 3. FIG. 4 is a graph showing a current waveform when the motor rotates when a drive current is supplied to the disk brake motor shown in FIG. 3. FIG. 4 is a graph showing a current waveform when the motor does not rotate when drive current is supplied to the motor of the disc brake shown in FIG. 3. It is a flowchart which shows the parking brake operation / release determination processing routine of the disc brake device which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Disc brake device, 5A Parking brake mechanism, 13 Parking brake controller (control means), 15 Disc rotor, 16 Brake pad, 18 Cylinder, 19 Piston, 28 Electric motor

Claims (4)

Mounted a pair of brake pads disposed on both sides of the disc rotor of a vehicle in the caliper for pressing the piston slidably provided in the cylinder, in braking position said piston front contact with Kipi Stone A parking brake mechanism having a screw mechanism for fixing , and a drive mechanism for operating the screw mechanism by an electric motor ;
In the disc brake system and a control means for controlling said electric motor,
The control means includes
Supplying a predetermined drive current to the electric motor to monitor the rotation of the electric motor;
When the electric motor rotates, it is determined that the parking brake is released,
When the electric motor does not rotate, it has a parking brake operation / release determination processing unit that determines that the parking brake is operating.
The parking brake operation / release determination processing unit performs a determination process at a predetermined timing from when the ignition switch of the vehicle is turned off to when it is turned on .   2. The predetermined timing is any one of when a door key unlocking is detected, when a door opening is detected by a door switch, or when an ignition switch is turned on. Disc brake device as described. 3. The disc brake according to claim 1, wherein the control unit supplies a drive current in a direction in which the piston presses the brake pad when supplying a predetermined drive current to the electric motor. 4. apparatus. 4. The disc brake according to claim 1, wherein the control unit stops the determination of the parking brake state when detecting that the hydraulic pressure is supplied into the cylinder. 5. apparatus.

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