12-8
Installation of steering
gear box and pipeInstallation of pipe
Installation of reservoir and hoseInstallation of power steering pump
and pipe
2. SYSTEM LAYOUT
The steering pump is driven by the engine power through a belt. This pump circulates the power steering
oil from the reservoir -> steering pump -> oil supply pipe -> steering gear box -> oil return pipe ->
reservoir to perform steering operations.
Return pipe
Supply pipe
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1. SPECIFICATION
Unit Description Specification
System operationOperating type Motor driven power steering system
Operating temperature- 40°C to 80°C
Rated voltage 12 V
Rated current 85 A
Operating voltageNetwork 8 to 16 V
C-EPS ECU 8 to 16 V
Full Performance 10 to 16 V
MotorType 3-Phase BLAC (Brushless AC)
Rated current/voltage 85 A / 12 V (at idle 0.5 A)
Position sensor type Hall sensor type
Torque & angle sensorType Non-contact type
Steering columnOperating type Manual tilting & telescoping
Lower shaftType Sliding (Ball slip) type
Steering gearGear ratio 46.94 mm/rev
Rack stroke 146 mm
Maximum steering angleInner wheel39°
Outer wheel31.24°
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3. DIFFERENCES BETWEEN HPS AND EPS
HPS EPS
1 Crankshaft pulley (DDU)
2 Auto tensioner
3 Tensioner pulley
4 Vacuum pump
5 A/C compressor pulley
6 Alternator pulley
7 Water pump pulley
8 No.1 idle pulley
9 No.2 idle pulley
10 Power steering pump -
HPS (Hydraulic Power Steering)EPS (Electric Power Steering)
13-6
Hydraulic power steering Electric power steering
1. OVERVIEW
The electric power steering, EPS, does not have any belt-driven steering pump constantly running, so it
is lightweight and the motor consumes energy only when the steering wheel is turned by the driver, and
this leads to improvement in fuel efficiency. Also, the elimination of a belt-driven pump and its
accessories greatly simplifies manufacturing and maintenance. While offering these benefits, as it does
not contain any steering oil, the environment is not polluted both when the steering system is produced
and discarded.
In other words, the electric power steering (EPS) system uses the electric motor to assist the steering
force. It functions independently regardless of whether the engine is running or not, unlike the existing
hydraulic power steering.
The EPS system generates an assist steering force variably depending on the driving conditions by
controlling the motor's operation, based on the input signals from the sensors such as torque sensor and
angle sensor. In turn, the EPS receives the torque signal by the driver's movements of the steering
wheel, as well as the vehicle speed, and uses the motor to determine the assist torque. The EPS
controls the motor for this. Another features of EPS are fail-safe function, diagnosis function,
communication function between units and interface function for external diagnostic device.
The EPS system components such as the torque sensor, steering angle sensor, fail-safe relay, etc. are
located in the steering column and EPS unit assembly.
Advantages: ▶
Assurance of improved steering
Provides optimal steering force according to the
vehicle speed
Enhanced steering stability while driving at high
speed (1)
-
-Reduced fuel consumption
Consumes energy only when steering wheel
is turned (improved by 3 to 5%)
Energy saving (reduced by 85% compared
with hydraulic power steering)
Reduced number of parts: Elimination of
steering pump, hydraulic hose, pump pulley,
oil reservoir, belt, bracket, etc. (2)
-
-
-
Comparison between hydraulic power steering and electric power steering (EPS) ▶
