ELECTRO-MECHANICAL STEERING SYSTEM

SUBMITTED BY-PAPPOO YADAVSR NO - 567/12

BRIEF HISTORY

The first automobiles were steered with a tiller.

A steering wheel was first used in Europe in 1894 .

Bicycles, Mobility scooters are often using tiller steering.

OTHER FEATURES…

It helps in swinging the wheels to the left or right.

It converts the rotary movement of the steering wheel into an angular turn of the front wheels.

It multiplies the effort of the driver by leverage in order to make it fairly easy to turn the wheels.

It absorbs a major part of the road shocks thereby preventing them to get transmitted to the hands of the driver

BASIC STEERING MECHANISM

Ackerman steering system

Davis steering system

Projected center lines of all should meet on or near the centre of the rear axle.

TYPES OF STEERING SYTEM

RECIRCULATING OR PARALLELOGRAM STEERING SYSTEM

RACK AND PINION TYPE STEERING SYSTEM

Any vehicle (heavy,small,medium) must have these two steering system whether they have any type of power steering.

RECIRCULATING TYPE

RECIRCULATING GEAR BOX

It consists of a worm at the end of steering rod.

The balls reduce the friction during the movement of the nut on the worm.

The nut has a number of teeth on outside, which mesh with the teeth on a worm wheel sector.

Used for heavy vehicle like trucks, buses etc.

RACK AND PINION TYPE

RACK AND PINION GEAR BOX

• Some cars have variable-ratio steering, which uses a rack-and-pinion gear set that has a different tooth pitch (number of teeth per inch) in the center than it has on the outside.

• This makes the car respond quickly when starting a turn (the rack is near the center), and also reduces effort near the wheel's turning limit.

• Used in small and medium vehicles like cars,suv,racing cars etc.

WHEEL ALIGNMENT

CAMBER ANGLECASTER ANGLETOE-IN AND TOE-OUTKING PIN INCLINATION

WHEEL ALIGNMMENT

Why is it necessary?

Directional stabilityMaintain straightnessReduce uneven wear of tyresProper traction between tyres and road while

turning

POWER STEERING

1. Hydraulic power steering(HPS)

2. Electro-mechanical steering system or electric steering system (EPS)

3. Electro hydraulic steering system(EHPS)

4. Hydrostatic steering system (no mechanical linkage, used in tractor, roller, bulldozer )

ELECTRO MECHANICAL STEERING SYSTEM

Why we need for this while we have manual as well as hydraulics steering system?

PROS OF EPS

Less complicated Usually less weighs There is no such fluid needed thus it needs less

maintenance compared to hydraulic power steering. Better response at different speeds It supports return of the steering wheel back to the

center position via the “active return” function. It consumes power from battery, but it consumes

less power compared to HPS. So a car having EPS will give more mileage than one with HPS.

Straight-line stability function No continuous power taking

EPS

• Electric Power Steering (EPS) is the latest system in which the electric motor (“E-motor”) is attached.

• Sensors detect the motion of the steering column and a processor module applies assistive power via an electric motor. This allows varying amounts of assistance depending on driving conditions.

• With electronic systems becoming more and more common in cars, EPS is the future power steering system that they will use.

• EPS is active only during the actual steering process.• The sum of the turning force on the steering wheel and the

assisting force is the effective force applied on the steering gear to move the rack.

DIFFERENT EPS SYSTEM THAT ARE IN USE

A. COLUMN TYPE The column drive is used

for small and lower mid-sized cars. The motor is located in the passenger compartment.

Its advantage is its better performance at reduced temperatures, and sealing.

DIFFERENT EPS SYSTEM THAT ARE IN USE

B. DUAL PINION TYPE

• The dual pinion drive is used for mid-sized cars.

• This drive is located in the engine compartment

DIFFERENT EPS SYSTEM THAT ARE IN USE

C. RACK TYPE

• This type is appropriate for large vehicles such as Sports Utility Vehicles(SUVs) and trucks

EPS COMPONENTS

1. Steering wheel2. Steering Angle Sensor G853. Steering column4. Steering Torque Sensor

G2695. Steering gear6. Electro-mechanical Power

Steering7. Motor V1878. Power Steering Control

Module J500

SYSTEM OVERVIEW

STEERING FUNCTION1. The power steering assistance starts when the driver uses force to turn the steering wheel

2. The Steering Torque Sensor detects the rotation and sends the calculated steering force figure to the Power Steering Control Module. 3. The Steering Angle Sensor reports the current steering angle and steering speed.

STEERING FUNCTION4. Depending on the steering force, road speed, engine speed, steering angle, steering speed and maps stored in Power Steering Control Module , it calculates the necessary assisting force and actuates EMPS Motor.

5. The steering assistance comes from asecond pinion, which applies its energyin parallel on the steering rack. Thispinion is driven by EMPS Motor.

6. The sum of the turning force on thesteering wheel and the assisting forceis the effective force applied on thesteering gear to move the rack.

STEERING FUNCTION

Electro-mechanical Power Steering Indicator Lamp EMPS Indicator Lamp light up in

two colors if functional faults are detected.

If it lights up yellow, the warning is of a lower priority.

If it lights up red, the vehicle should be serviced immediately

Once Power Steering Control Module receives a signal, indicating that all systems are working correctly, EMPS Indicator Lamp will go out.

CONTROL MAP CHARACTERISTICS

ENERGY COSUMPTION

EPS EHPS HPS HSPS0

10

20

30

40

50

60

70

80

90

100

10

35

60

100

CONCLUSION

EPS reduces the human effort up to 80 percent so upcoming year of steering will be of EPS in all type of vehicle.

EPS will become most efficient, safe and reliable power steering system in the future .

The key to the success of EPS is an accurate and quick response, so it will be used in F1 racing cars in upcoming years.

Program for control module IC can be changed according to need of assisting force. So it will be beneficial for different types of road.

This year, in auto spa Delhi, mostly cars manufactured by different company were launched with EPS.

REFERENCES

www.autoshop101.com/forms/Hybrid17.pdf http://www.volkspage.net/technik/ssp/ssp/SSP_225.pdf

self study program 259 http://www.howeperformance.com/rockcrawling.html R.K.RAJPUT, 2009-10 , “AUTOMOBILE ENGINEERING”M.F. Rehman, “ELECTRIC POWER ASSISTED STEERING

SYSTEM FOR AUTOMOBILES”, Electrical Engineering Vol.3.

Ratan S., Tata McGraw Hills publication , “Theory of Machines” Vol 1,

www.infineon.com/electric power steering.pdf/Edition 2008-10-23