ANTILOCK BRAKINH SYSTEM
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (374.08 KB, 14 trang )
ANTILOCK BRAKING SYSTEM
Le Thanh Phuc
Faculty of Automotive Engineering
University of Technical Education Ho Chi Minh City
Email:
Introduction
• ABS is a safety-related feature that assists the driver in deceleration
of the vehicle in poor or marginal braking conditions (e.g. wet or icy
roads).
• In ABS-equipped cars, the wheel is prevented from locking by a
mechanism that automatically regulates the force applied to the
wheels by the brakes to an optimum for any given low-friction
condition.
Slip ratio
• The car is traveling at a speed U and the wheels are rotating at an
angular speed ωw where
and where RPMw is the RPM of the wheel in revolutions per
minute. When the wheel is rolling (no applied brakes)
where rw is the tire effective radius.
• The braking and lateral forces are proportional to the normal force
(from the weight of the car and from inertial forces due to
deceleration) acting on the tire/road interface and the friction
coefficients for braking force (Fb)
• The torque Tw applied to the wheel at the road surface by the
braking force Fb
• The braking torque Tb is applied to the disk by the brake pads in
response to brake pressure pb
• In accordance with basic Newtonian mechanics, the wheel torque
Tw is related to braking torque and wheel deceleration by the
following equation:
• The longitudinal motion of the vehicle is described:
.
mU = ∑ F b
where m is vehicle mass, Fb is force acting on the tires when braking
