Electrically Driven Brake Booster

• US 20110074209A1
• Filed: 08/13/2010
• Published: 03/31/2011
• Est. Priority Date: 09/30/2009
• Status: Active Grant

• Current Assignee: Hitachi Astemo Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi Automotive Systems Limited (Hitachi, Ltd.)
• Inventors: UENO, Kentaro
• Granted Patent: US 8,991,940 B2
• Time in Patent Office: Days
• US Class Current: 303/20
• CPC Class Codes: B60T 13/745 acting on a hydraulic system, e.g. a master cylinder

Abstract

In an electrically driven brake booster wherein an electrically driven actuator moves a booster piston upon operation of a brake pedal to generate a hydraulic pressure for driving a brake force at the maser cylinder, the electrically driven actuator controls to move the booster piston as the pressing member in order to correctly detect presence/absence of an operation of the booster piston and detect a movement pattern of an input rot and an input piston as the shaft member relative to a movement of the pressing member. In accordance with the movement pattern, presence/absence of an operation of the brake pedal is detected. By confirming that the brake pedal is not operated, by the method described above, a zero point of a stroke sensor for detecting the position of the shaft member and zero points of oil pressure sensors for detecting a hydraulic pressure supplied by the master cylinder are learnt.

Claims

1. An electrically driven brake booster comprising:

a master cylinder for generating a hydraulic pressure to be used for generating a vehicle brake force;

a pressing member for controlling a hydraulic pressure generated by said master cylinder;

an electrically driven actuator for moving said pressing member forward and backward;

a sensor to be used for measuring a movement amount or position of said pressing member; and

a controller,

wherein;

said controller controls said electrically driven actuator in accordance with an operation of a brake pedal to control a hydraulic pressure to be generated by said master cylinder; and

said controller obtains a position or a movement reference point of said pressing member through a learning operation.

2. An electrically driven brake booster according to claim 1, further comprising:

a fixed member mounted on a fixed position; and

a moving member for moving in correspondence with a movement of said pressing member,

wherein said controller detects that said moving member reaches a position of said fixed member, and learns said reference point in response to the detection.

3. An electrically driven brake booster according to claim 2, wherein:

said fixed member is a first stopper provided along a movement axis of forward and backward movement of said pressing member;

said moving member is a second stopper moving together with said pressing member; and

said controller learns said reference position point in response to that said second stopper moving together with said pressing member contacts said first stopper.

4. An electrically driven brake booster according to claim 2, wherein:

said controller uses as a standby position a position of said pressing member where said master cylinder does not generate a hydraulic pressure for generating the brake force, and said fixed member is provided at a position remote from said master cylinder than said standby position;

when an operation state of the brake pedal is changed to a state that the brake pedal is not operated, said controller controls said electrically driven actuator to move said pressing member to said standby position; and

in the learning operation, said controller controls said electrically driven actuator so as to make said moving member reach a position of said fixed member.

14. The electrically driven brake booster according to claim 1, wherein learning of a zero point of said sensor is performed under a condition that a vehicle is accelerated.

5. An electrically driven brake booster comprising:

a master cylinder for generating a hydraulic pressure to be used for generating a vehicle brake force;

a pressing member for controlling a hydraulic pressure generated by said master cylinder;

an electrically driven actuator for moving said pressing member forward and backward;

a pressure sensor to be used for measuring a hydraulic pressure generated by said master cylinder; and

a controller,

wherein;

said controller controls said electrically driven actuator in accordance with an operation of a brake pedal to control a hydraulic pressure to be generated by said master cylinder; and

said controller detects a state that the brake pedal is not operated, and in response to the detection, a zero point of said pressure sensor is detected through a learning operation.

6. The electrically driven brake booster according to claim 5, wherein:

said controller detects a state that the break pedal is not operated, and in the state that the brake pedal is not operated, performs learning of a position or a movement reference point of said pressing member; and

learning of said pressure sensor is performed at a higher frequency than learning of the reference point of said movement amount reference point.

7. An electrically driven brake booster comprising:

a shaft member for moving forward and backward in accordance with an operation of a brake pedal;

a master cylinder for generating a hydraulic pressure to be used for generating a brake force;

a pressing member for controlling a hydraulic pressure generated by said master cylinder;

an electrically driven actuator for moving said pressing member forward and backward;

a sensor to be used for measuring a movement amount or position of said pressing member; and

a controller,

wherein;

said controller controls said electrically driven actuator in accordance with an operation of a brake pedal to control a hydraulic pressure to be generated by said master cylinder; and

said controller detects a state that the brake pedal is not operated, and in the state that the brake pedal is not operated, obtains a position or movement reference point of said pressing member through a learning operation.

8. An electrically driven brake booster according to claim 7, further comprising:

a fixed member mounted on a fixed position; and

a moving member for moving in correspondence with a movement of said pressing member,

wherein said controller detects that said moving member reaches a position of said fixed member, and learns said reference point in response to the detection.

9. An electrically driven brake booster according to claim 8, wherein:

said fixed member is a first stopper provided along a movement axis of forward and backward movement of said pressing member;

said moving member is a second stopper moving together with said pressing member; and

said controller learns said reference position point in response to that said second stopper moving together with said pressing member contacts said first stopper.

10. An electrically driven brake booster according to claim 8, wherein:

said controller uses as a standby position a position of said pressing member where said master cylinder does not generate a hydraulic pressure for generating the brake force, and said fixed member is provided at a position remote from said master cylinder than said standby position;

when an operation state of the brake pedal is changed to a state that the brake pedal is not operated, said controller controls said electrically driven actuator to move said pressing member to said standby position; and

in the learning operation, said controller controls said electrically driven actuator so as to make said moving member reach a position of said fixed member.

13. The electrically driven brake booster according to claim 7, wherein said controller moves said pressing member in order to detect a state that the brake pedal is not operated, detects a movement of said shaft member caused by a movement of said pressing member, and judges presence/absence of an operation of the brake pedal in accordance with a movement of said shaft member.

11. An electrically driven brake booster comprising:

a master cylinder for generating a hydraulic pressure to be used for generating a vehicle brake force;

a pressing member for controlling a hydraulic pressure generated by said master cylinder;

an electrically driven actuator for moving said pressing member forward and backward;

a pressure sensor to be used for measuring a hydraulic pressure generated by said master cylinder; and

a controller,

wherein;

said controller controls said electrically driven actuator in accordance with an operation of a brake pedal to control a hydraulic pressure to be generated by said master cylinder; and

said controller detects a state that the brake pedal is not operated, and in response to the detection, detects a zero point of said pressure sensor through a learning operation.

12. The electrically driven brake booster according to claim 11, wherein:

said controller detects a state that the brake pedal is not operated, and in the state that the brake pedal is not operated, performs learning of a position or a movement reference point of said pressing member; and

learning of a zero point of said pressure sensor is performed at a higher frequency than learning of said movement reference point.