Lexus ES300 (2002 year). Manual — part 108
CHASSIS – BRAKE
CH-54
182CH56
Rear
Brake
Force
Rear
Brake
Force
Ideal Brake Force
Distribution
EBD Control
Front Brake Force
Front Brake Force
EBD Control
Ideal Brake Force Distribution
without Load in Rear
with Load in Rear
181CH56
Front / Rear Wheels Brake Force Distribution
If the brakes are applied while the vehicle is moving straight forward, the transfer of the road reduces the
load that is applied to the rear wheels. The skid control ECU determines this condition by way of the signals
from the speed sensor, and the brake actuator regulates the distribution of the brake force of the rear wheels
to optimally control.
For example, the amount of the brake force that is applied to the rear wheels during braking varies whether
or not the vehicle is carrying a load. The amount of the brake force that is applied to the rear wheels also
varies in accordance with the extent of the deceleration.
Thus, the distribution of the brake force to the rear is optimally controlled in order to effectively utilize the
braking force of the rear wheels under these conditions.
EBD Control Concept
Right / Left Wheels Brake Force Distribution (During Cornering Braking)
When the brakes are applied while the vehicle is
cornering, the load that applied to the inner
wheel decreases to the outer wheel increases.
The skid control ECU determines this condition
by way of the signals from the speed sensor, and
the brake actuator regulates the brake force in
order to optimally control the distribution of the
brake force to the inner wheel and outer wheel.
CHASSIS – BRAKE
CH-55
211CH29
ABS Warning Light
Brake System
Warning Light Combination Meter
Speed Sensors
Speed Sensors
Brake Actuator
Skid Control ECU
Stop Light Switch
4. Layout of Component
5. Function of Component
Component
Function
Combination
ABS Warning Light
Lights up to alert the driver when the skid control ECU detects the
malfunction in the ABS.
Combination
Meter
Brake System
Warning Light
Lights up together with the ABS warning light to alert the driver
when the skid control ECU detects the malfunction in the EBD
control.
Brake Fluid Level Warning Switch
Detects the brake fluid level.
Stop Light Switch
Detect the brake pedal depressing signal.
Speed Sensors
Detect the wheel speed of each four wheels.
Brake
Actuator
Actuator Portion
Charges the fluid path based on the signals from the skid control
ECU during the operation of the ABS with EBD system, in order
to control the fluid pressure that is applied to the wheel cylinders.
Actuator
Skid Control ECU
Judges the vehicle driving condition based on signals from each
sensor, and sends brake control signal to the brake actuator.
CHASSIS – BRAKE
CH-56
211CH30
Actuator
Portion
Skid Control
ECU
208CH25
Brake Actuator
Front Left
Rear Right
Rear Left
Front Right
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
6. Brake Actuator
General
The brake actuator consists of actuator portion
and skid control ECU.
Actuator Portion
1) Construction
The brake actuator consists of 8 two-position solenoid valves, 1 motor, 2 pumps and 2 reservoirs.
The 8 two-position solenoid valves consists of 4 pressure holding valves [(1), (2), (3), (4)], and 4 pressure
reduction valves [(5), (6), (7), (8)].
Hydraulic Circuit
CHASSIS – BRAKE
CH-57
169CH56
169CH55
169CH54
Port A
Pressure Holding Valve
Port B
Pressure
Reduction Valve To Wheel
Cylinder
To
Reservoir
and Pump
From Wheel
Cylinder
2) ABS with EBD Operation
Based on the signals received from the 4 wheel speed sensors, the skid control ECU calculates each wheel
speed and deceleration, and checks wheel slipping condition. And according to the slipping condition,
the ECU controls the pressure holding valve and pressure reduction valve in order to adjust the fluid
pressure of each wheel cylinder in the following 3 modes: pressure reduction, pressure holding, and
pressure increase modes.
Not Activated
Normal Braking
—
—
Activated
Increase Mode
Holding Mode
Reduction Mode
Hydraulic
Circuit
Pressure
Holding Valve
(Port A)
OFF (Open)
ON (Close)
ON (Close)
Pressure
Reduction Valve
(Port B)
OFF (Close)
OFF (Close)
ON (Open)
Wheel Cylinder
Pressure
Increase
Hold
Reduction
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст