IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
UP-0546947
(2009-08-25)
|
등록번호 |
US-7828124
(2010-11-25)
|
우선권정보 |
JP-2008-221799(2008-08-29) |
발명자
/ 주소 |
- Sano, Kazumoto
- Usui, Takuya
|
출원인 / 주소 |
- Hitachi Automotive Systems, Ltd.
|
대리인 / 주소 |
Wenderoth, Lind & Ponack, L.L.P.
|
인용정보 |
피인용 횟수 :
5 인용 특허 :
4 |
초록
▼
An electric disk brake is capable of determining an abnormality of a parking brake mechanism while the parking brake mechanism is in operation. A brake force is generated in the following manner. A rotation of an electric motor is slowed down by a differential speed reducing mechanism, and is conver
An electric disk brake is capable of determining an abnormality of a parking brake mechanism while the parking brake mechanism is in operation. A brake force is generated in the following manner. A rotation of an electric motor is slowed down by a differential speed reducing mechanism, and is converted into a linear motion by a ball ramp mechanism so as to advance a piston, which then presses a brake pad against a disk rotor to generate a brake force. A parking brake mechanism can lock a rotation of a rotor of the electric motor and maintain a braked state by rotating an engagement pawl through a plunger of a solenoid and causing the engagement pawl to be engaged with a ratchet wheel coupled to the rotor of the electric motor. A play is provided at a coupling portion of the engagement pawl and the plunger. The play enables the plunger to move within the range of the play while the engagement pawl is engaged with the ratchet wheel, thereby enabling the determination of whether the parking brake mechanism operates normally or abnormally based on whether the plunger moves or not upon application of an electric current to the solenoid while the parking brake mechanism is in an actuated state.
대표청구항
▼
What is claimed is: 1. An electric disk brake for generating a brake force by converting a rotational motion of a motor into a linear motion so as to advance a piston, and for pressing a brake pad against a disk rotor with the piston, the electric disk brake comprising: a parking brake mechanism in
What is claimed is: 1. An electric disk brake for generating a brake force by converting a rotational motion of a motor into a linear motion so as to advance a piston, and for pressing a brake pad against a disk rotor with the piston, the electric disk brake comprising: a parking brake mechanism including a solenoid, a plunger, and a lock mechanism, the parking brake mechanism being operable to hold a generated brake force by causing the solenoid to move the plunger in an actuating direction so as to actuate the lock mechanism; and a control apparatus operable to control the solenoid; wherein the parking brake mechanism includes a play between the plunger and the lock mechanism or in the lock mechanism, the play allowing the plunger to be moved in the actuating direction at least while the lock mechanism is in a locked state; and wherein the control apparatus includes a parking brake mechanism abnormality determining unit operable to determine whether the parking brake mechanism operates normally or abnormally by applying an electric current to the solenoid so as to cause a movement of the plunger within the play while the lock mechanism is in the locked state. 2. The electric disk brake according to claim 1, wherein the parking brake mechanism abnormality determining unit determines that the parking brake mechanism operates normally if the parking brake mechanism abnormality determining unit detects movement of the plunger within the play, and determines that the parking brake mechanism operates abnormally if the parking brake mechanism abnormality determining unit detects no movement of the plunger within the play. 3. The electric disk brake according to claim 2, wherein whether or not the plunger is moved is detected based on an electric current supplied to the solenoid. 4. The electric disk brake according to claim 3, wherein the parking brake mechanism abnormality determining unit determines that the parking brake mechanism operates normally if the electric current supplied to the solenoid is reduced due to the movement of the plunger, and determines that the parking brake mechanism operates abnormally if the electric current supplied to the solenoid continues to increase during a predetermined time period. 5. The electric disk brake according to claim 2, wherein whether or not the plunger is moved is detected based on a position of the plunger. 6. The electric disk brake according to claim 2, wherein whether or not the plunger is moved is detected based on a change in an inductance of the solenoid. 7. The electric disk brake according to claim 1, further comprising a motor abnormality determining unit operable to determine whether the motor operates normally or abnormally by trying to rotate the motor in a direction causing the brake pad to be pressed against the disk rotor. 8. The electric disk brake according to claim 1, wherein the control apparatus is operable to initiate a re-clamp operation in which the parking brake mechanism is re-actuated, and wherein the control apparatus prohibits the re-clamp operation if the parking brake mechanism abnormality determining unit determines that the parking brake mechanism operates abnormally. 9. The electric disk brake according to claim 8, wherein, in a case where a vehicle has the electric disk brake for each of a plurality of wheels, when the re-clamp operation is prohibited in one of the wheels, a force of pressing the brake pad against the disk rotor in the re-clamp operation is increased in the other wheels. 10. The electric disk brake according to claim 1, wherein the lock mechanism includes a ratchet wheel adapted to rotate according to the rotational motion of the motor, the ratchet wheel including a plurality of teeth, and an engagement pawl adapted to be engaged with any of the teeth of the ratchet wheel so as to prevent a rotation of the ratchet wheel, wherein the plunger is operable to cause the engagement pawl to be engaged any of the teeth of the ratchet wheel, and wherein the play is provided between the engagement pawl and the plunger for enabling the plunger to be moved. 11. The electric disk brake according to claim 1, wherein the lock mechanism includes a ratchet wheel adapted to rotate according to the rotational motion of the motor, the ratchet wheel including a plurality of teeth, and an engagement pawl adapted to be engaged with any of the teeth of the ratchet wheel so as to prevent a rotation of the ratchet wheel, wherein the plunger is operable to cause the engagement pawl to be engaged any of the teeth of the ratchet wheel, and wherein the play is provided between the engagement pawl and the teeth of the ratchet wheel for enabling the plunger to be moved. 12. An electric disk brake, comprising: a motor; a converting mechanism operable to convert a rotational motion of the motor into a linear motion; a piston adapted to be advanced by the linear motion of the converting mechanism; a brake pad adapted to be pressed against a disk rotor by the advance of the piston; a parking brake mechanism including a solenoid, a plunger, and a lock mechanism, the parking brake mechanism being operable to hold a brake force generated by the pressure of the brake pad by causing the solenoid to move the plunger in an actuating direction so as to actuate the lock mechanism; and a control apparatus operable to control the parking brake mechanism and the motor, wherein the parking brake mechanism includes a play between the plunger and the lock mechanism or in the lock mechanism, the play allowing the plunger to be moved in the an actuating direction within a predetermined range that does not cause a release of a locked state of the lock mechanism, and wherein the control apparatus includes a parking brake mechanism abnormality determining unit adapted to apply an electric current to the solenoid while the lock mechanism is in the locked state and detect whether or not the plunger moves, the parking brake mechanism abnormality determining unit determining that the parking brake mechanism operates normally if the plunger moves within the predetermined range and determining that the parking brake mechanism operates abnormally if the plunger does not move within the predetermined range. 13. The electric disk brake according to claim 12, further comprising a motor abnormality determining unit operable to determine whether the motor operates normally or abnormally by trying to rotate the motor in a direction causing the brake pad to be pressed against the disk rotor. 14. The electric disk brake according to claim 12, wherein the control apparatus is operable to initiate a re-clamp operation in which the parking brake mechanism is re-actuated, and wherein the control apparatus prohibits the re-clamp operation if the parking brake mechanism abnormality determining unit determines that the parking brake mechanism operates abnormally. 15. The electric disk brake according to claim 12, wherein whether or not the plunger is moved is detected based on an electric current supplied to the solenoid. 16. The electric disk brake according to claim 12, wherein whether or not the plunger is moved is detected based on a change in an inductance of the solenoid. 17. An electric disk brake, comprising: a motor; a converting mechanism operable to convert a rotational motion of the motor into a linear motion; a piston adapted to be advanced by the linear motion of the converting mechanism; a brake pad adapted to be pressed against a disk rotor by the advance of the piston; a parking brake mechanism operable to hold a brake force generated by the pressure of the brake pad; and a control apparatus operable to control the parking brake mechanism and the motor; and wherein the parking brake mechanism includes (i) a ratchet wheel adapted to rotate according to the rotational motion of the motor, the ratchet wheel including a plurality of teeth, (ii) an engagement pawl adapted to be engaged with any of the teeth of the ratchet wheel so as to prevent a rotation of the ratchet wheel, (iii) a plunger operable to cause the engagement pawl to be engaged with one of the teeth of the ratchet wheel, and (iv) a solenoid for moving the plunger in an actuating direction so as to actuate the engagement pawl; wherein the parking brake mechanism includes a play between the engagement pawl and the teeth of the ratchet wheel or between the engagement pawl and the plunger, the play allowing the plunger to be moved in the actuating direction thereof while the engagement pawl is engaged with one of the teeth of the ratchet wheel; and wherein the control apparatus comprises a parking brake mechanism abnormality determining unit adapted to apply an electric current to the solenoid while the engagement pawl is engaged with one of the teeth of the ratchet wheel and detect whether or not the plunger moves, the parking brake mechanism abnormality determining unit determining that the parking brake mechanism operates normally if the plunger moves within the play and determining that the parking brake mechanism operates abnormally if the plunger does not move. 18. The electric disk brake according to claim 17, wherein the parking brake mechanism abnormality determining unit determines that the parking brake mechanism operates normally if the electric current supplied to the solenoid is reduced due to the movement of the plunger, and determines that the parking brake mechanism operates abnormally if the electric current supplied to the solenoid continues to increase during a predetermined time period. 19. The electric disk brake according to claim 17, wherein the play is provided between the engagement pawl and an of the teeth of the ratchet wheel, and wherein the control apparatus causes the motor to rotate the ratchet wheel in a direction causing the brake pad to be pressed against the disk rotor before the plunger is moved in determining whether the parking brake mechanism operates normally, so that a load acting between the engagement pawl and the tooth is released while the engagement between the engagement pawl and the tooth is kept. 20. The electric disk brake according to claim 19, further comprising a motor abnormality determining unit operable to determine whether the motor operates normally or abnormally when the ratchet wheel is provided through the motor with the force for the rotation in the direction causing the brake pad to be pressed against the disk rotor.
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