Page 360 of 465
0-21
ABS SYSTEM
RODIUS 2006.09
4892-01
(3) COMPONENTS DESCRIPTION
HECU (Hydraulic & Electronic Control Unit) ▶
Motor Pump ▶
Valve Body ▶
HECU consists of motor pump (1), solenoid
valve (2) and ECU (3).
ECU connector has 47 pins and the numbe
r
of valves in valve body is 6 when equipped
with only ABS and 12 when equipped with
ESP system.
The motor is operated when ABS is
activated. The cam-shaped output shaft o
f
the motor enables the brake system to
receive and supply the brake fluid during the
motor operation.
The cam bushing is installed between
plungers and it draws and discharges the
brake fluid.
Page 361 of 465
0-22
RODIUS 2006.09
4892-01
ABS SYSTEM
Pumping
▶
ECU (Including Solenoid Valves ? ESP Equipped Model)
▶
ECU lower cover)
▶
When the cam pushes the left plunger
during motor operation, the system pressure
is generated in the left cylinder. At this time,
the right plunger is expanded by spring force
and the expanded volume of the right
cylinder draws the brake fluid.
HECU controls the hydraulic valves by
supplying or cutting off the voltage to
solenoid valves depending on the wheel
speed and other information from wheel
speed sensors.
The figure shown in left side is for ESP
ECU. There are two channels for front
wheels and one channel for rear wheels.
Each channel has one inlet and one outlet
valve, therefore,
there are six solenoid valves.
The electrical components are weak to
moisture. To protect ECU, GoreTex-based
plate is used at ECU lower cover. The vent
hall (arrow) allows air to ventilate but does
not allow moisture to penetrate.
Page 372 of 465
0-7
WHEEL
RODIUS 2006.09
4710-09
2. TIRE’S ABNORMAL PHENOMENA
1) Standing Wave
2) Hydroplaning
During running the rotating tire repeats
deformation and restoring movement
generated in tread. But when the wheel
rotating speed reaches high, the next
deformation applied to tire before restoring
last deformation so the trembling wave
appears in the tread portion. The lower the
tire pressure the severe the trembling wave
appears during the high speed.
The condition of driving a vehicle fast on the
road surface covered with water can cause
tires to fail to rotate with a good contact on
the surface, so results in remaining them a
float. This is so-called hydroplaning. It
causes brake failure, lower tractive force
and losing the steering performance so it is
very vulnerable condition.