Seminar on ELECTRONIC POWER STEERING N.L.BINDUKUMAR 1BI04ME404

Introduction Steering is the term applied to the collection of components, linkages, etc. which allow for a car or other vehicle to follow a course determined by its driver. Vehicle performance depends highly on good steering control, which provides an accurate feedback about how the vehicle reacts to the road.

What is Power steering? Power steering is a system for reducing the steering effort on cars by using an external power source to assist in turning the wheels. Most new vehicles now have power steering.

Does your car have power assisted steering and how do you know? Power steering can be identified when parking the car. Also when moving the car very slowly. When car is stationary it requires considerable effort to turn the wheel.

Working of Power Steering  

Rotary valve pump

Rack and Pinion The device that senses the force on the steering wheel is called the rotary valve. The rotary valve is connected to steering gear and gives the applied torque means required turn.

Advantages of using Power Steering Requires minimal physical exertion. Very fast to turn lock to lock without much force. Can be set up permitting vehicle to travel in a straight line without driver input on a constant camber road in still conditions. Blowouts etc. cannot affect steering wheel or the direction of the steered wheel which can only be moved by steering wheel input.

Types of power steering Hydraulic power steering Electrical/Electronic power steering

Disadvantages of Hydraulic power steering Complex and high cost. “on” all the time and powered by engine-low fuel economy and safety concern. Hard to integrate new technologies in.

Electronic power steering What it is? 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 significant energy savings.

Electric power steering system layout Electric power steering does away with the pump, the hoses and the fluids. Instead, an electric motor provides the drive. The motor is placed either on the steering column, in the steering rack or in the linkage between the two.

Electronic power steering Electric power assisted steering (EPS) uses an electric motor to provide directional control to the driver. Most EPS systems have variable assist, which provides more assistance as the speed of a vehicle decreases and less assistance from the system during high-speed situations. This functionality requires a delicate balance of power and control that has only been available in recent years. The EPS system is replacing the hydraulic steering system and is destined to soon become mainstream among automotive manufacturers.

Advantages of EPS System Reduce maintenance and recycling cost. Reduced assembly time (up to 4 min). Up to 4% improvement in fuel economy. Enhanced safety (still operates even if engine is stalled). Possible for lane keeper, active tuning, chassis control integration.

Case Study: Electronic Power Steering Next Generation of EPS system Further cost reduction for design, testing, manufacturing/assembly, and warranty service. Advanced functions to enhance reliability and safety: fault-detection and tolerant, part erosion compensation, etc. Higher torque generation and optimized power flow management.

References Automobile Mechanics by N.K.Giri,Khanna publishers 2002 Industrial Maintenance, H.P Garg 2003 Basic Automotive Service and Systems By Jay Webster, Clifton E.Owen Web References: http://en.wikipedia.org/wiki/powersteering http://ieee.org http://howstuffworks/Electronicpowersteering

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