Electric braking system for vehicle

Patent metadata

Field	Value
Publication number	US-9505385-B2
Application number	US-201414776110-A
Country	US
Kind code	B2
Filing date	Mar 17, 2014
Priority date	Mar 15, 2013
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

When a braking operation amount is reduced, a stiffness value representing a ratio of variation in actual pressing force of a friction member to a variation in actual position of an electric motor are sequentially computed. The actual position when the stiffness value changes from being higher than or equal to a predetermined value to being lower than the predetermined value is stored as a candidate position. When a duration during which the stiffness value is lower than the predetermined value is shorter than a clearance corresponding value corresponding to a transmission member clearance in a state where the candidate position is stored, the candidate position is deleted. When the duration during which the stiffness value is lower than the predetermined value exceeds the clearance corresponding value, the stored candidate position is determined as a reference position at which the friction member and the rotary member begin contacting each other.

First claim

The invention claimed is:

1. An electric braking system for a vehicle, including:
braking operation amount acquisition means for acquiring a driver's braking operation amount of a braking operation member of the vehicle;
braking means for generating a braking torque in a wheel of the vehicle by transmitting power of an electric motor via a transmission member to press a friction member against a rotary member fixed to the wheel; and
control means for computing a target energization amount on the basis of the braking operation amount and controlling the electric motor on the basis of the target energization amount,
the electric braking system comprising:
pressing force acquisition means for acquiring an actual pressing force that is a force that the friction member actually presses the rotary member; and
position acquisition means for acquiring an actual position of the electric motor, wherein
the control means is configured to,
when the braking operation amount is reduced,
sequentially compute a stiffness value that is a ratio of a variation in the actual pressing force to a variation in the actual position;
store, as a candidate position, the actual position at time at which the stiffness value changes from a state higher than or equal to a predetermined value to a state lower than the predetermined value;
when a duration of the state where the stiffness value is lower than the predetermined value is shorter than a clearance corresponding value corresponding to a clearance in the transmission member in a state where the candidate position is stored, delete the candidate position;
at time at which the duration of the state where the stiffness value is lower than the predetermined value exceeds the clearance corresponding value in the state where the candidate position is stored, determine the stored candidate position as a reference position at which the friction member and the rotary member begin to contact with each other; and
compute the target energization amount on the basis of the reference position.

2. An electric braking system for a vehicle, including:
braking operation amount acquisition means for acquiring a driver's braking operation amount of a braking operation member of the vehicle;
braking means for generating a braking torque in a wheel of the vehicle by transmitting power of an electric motor via a transmission member to press a friction member against a rotary member fixed to the wheel; and
control means for computing a target energization amount on the basis of the braking operation amount and controlling the electric motor on the basis of the target energization amount,
the electric braking system comprising:
pressing force acquisition means for acquiring an actual pressing force that is a force that the friction member actually presses the rotary member; and
position acquisition means for acquiring an actual position of the electric motor, wherein
the control means is configured to,
when the braking operation amount is reduced,
sequentially compute a stiffness value that is a ratio of a variation in the actual pressing force to a variation in the actual position;
store, as a candidate force, the actual pressing force at time at which the stiffness value changes from a state higher than or equal to a predetermined value to a state lower than the predetermined value;
when a duration of the state where the stiffness value is lower than the predetermined value is shorter than a clearance corresponding value corresponding to a clearance in the transmission member in a state where the candidate force is stored, delete the candidate force;
at time at which the duration of the state where the stiffness value is lower than the predetermined value exceeds the clearance corresponding value in the state where the candidate force is stored, determine the stored candidate force as a correction pressing force corresponding to a zero-point drift of the pressing force acquisition means; and
compute the target energization amount on the basis of the correction pressing force.

3. An electric braking system for a vehicle, including:
braking operation amount acquisition means for acquiring a driver's braking operation amount of a braking operation member of the vehicle;
braking means for generating a braking torque in a wheel of the vehicle by transmitting power of an electric motor via a transmission member to press a friction member against a rotary member fixed to the wheel; and
control means for computing a target energization amount on the basis of the braking operation amount and controlling the electric motor on the basis of the target energization amount,
the electric braking system comprising:
pressing force acquisition means for acquiring an actual pressing force that is a force that the friction member actually presses the rotary member; and
position acquisition means for acquiring an actual position of the electric motor, wherein
the control means is configured to,
when the braking operation amount is reduced,
sequentially store a position data group for the actual position and a pressing force data group for the actual pressing force while the actual position is changing from a start position that is one of end points of a storage section, including an ineffective displacement section in which the actual position reduces but the actual pressing force does not reduce, to an end position that is the other one of the end points of the storage section;
determine a reference position, at which the friction member and the rotary member begin to contact with each other, on the basis of the position data group and the pressing force data group; and
compute the target energization amount on the basis of the reference position.

4. An electric braking system for a vehicle, including:
braking operation amount acquisition means for acquiring a driver's braking operation amount of a braking operation member of the vehicle;
braking means for generating a braking torque in a wheel of the vehicle by transmitting power of an electric motor via a transmission member to press a friction member against a rotary member fixed to the wheel; and
control means for computing a target energization amount on the basis of the braking operation amount and controlling the electric motor on the basis of the target energization amount,
the electric braking system comprising:
pressing force acquisition means for acquiring an actual pressing force that is a force that the friction member actually presses the rotary member; and
position acquisition means for acquiring an actual position of the electric motor, wherein
the control means is configured to,
when the braking operation amount is reduced,
sequentially store a position data group for the actual position and a pressing force data group for the actual pressing force while the actual position is changing from a start position that is one of end points of a storage section, including an ineffective displacement section in which the actual position reduces but the actual pressing force does not reduce, to an end position that is the other one of the end points of the storage section;
determine a correction pressing force, corresponding to a zero-point drift of the pressing force acquisition means, on the basis of the position data group and the pressing force data group; and
compute the target energization amount on the basis of the correction pressing force.

Assignees

• Yasui Yoshiyuki
• Kodama Hiroyuki
• SATAKE Naotoshi
• Advics Co Ltd

Inventors

• Yasui Yoshiyuki
• Kodama Hiroyuki
• SATAKE Naotoshi

Classifications

• F16D55/225

  the braking members being brake pads · CPC title

• B60T8/172 Primary

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title

• B60T13/741 Primary

  acting on an ultimate actuator · CPC title

• B60T8/3255

  Systems in which the braking action is dependent on brake pedal data · CPC title