DHANANJAY RAOBy

Electric Power Steering

What is Electric power steering system ?

Electrically powered steering uses an electric motor to drive either the power steering hydraulic pump or the steering linkage directly. The power steering function is therefore independent of engine speed, resulting in specific energy savings.

Electric power steering system

Hydraulic power steering system uses hydraulic pump Which is run by electric motor.

Where as, in EPS system electric motor is directly attached to steering rack via gear mechanism (no pump or fluid)

Electric Motor Location Types

COLUMN TYPE PINION TYPE RACK TYPE DOUBLE PINION

TYPE

EPS system consists of:-

Torque Sensor E C U ( Electronic Control

Unit ) Electric Motor Reduction Gear

Operational Mechanism Of EPS

Classification of EPS

The E P S system literally means that steering operation is entirely done by electronic /electrical means and no mechanical linkage exists between steering wheel and steered rod wheels.

Basically two formations are possible, they are,

1.Using Steering Wheel Control2.Using Joystick Control

Electronic Control System

Sensors Positive Sensors Digital Positive Sensors Speed Sensors E C U ( Electronic Control Unit )ActuatorsPower Supply

Construction and Working

Construction and Working (Contd…)

Comparison between EPS and HPS

Simple in DesignLighter in WeightRequire less maintenance as

hydraulic fluid is not usedGives better responses at different

speedBecause of less problem & faults

thus, it is durable than H P SMore mileage

ADVANTAGES

Increased reliability Improved fuel economy As hydraulic fluid is not needed it is

environment friendly Simplify Design Using joystick only one hand is sufficient to

drive the vehicle Self-diagnostic systems makes

maintenance easy and cheap 

APPLICATIONS

E P S can be incorporated into all passenger car and truck platforms. Since this system is compact and lightweight, it finds wide application in sports cars. Similar type of system is employed In India on Maruti-Suzuki Versa Van, ZenVXI, and Wagonr LXI etc.

Electric power steering can be found on the Acura NSX (Which was the first production car with this feature), the Honda S2000, Toyota Prius and Toyota RAV4,plus numerous. GM models including 2004-2009 Chevrolet Malibu, 2005-2009 Chevrolet Cobalt and Equinox, 2006-2009 Chevrolet HHR, 2005-2009 Pontiac G6 (except the convertible, GTP and 2007 GT models), 2006-2009 Pontiac Torrent, 2007-2009 Pontiac G5, 2002-2009 Saturn VUE, and 2003-2008 Saturn 10N.