米其林低滚动阻力轮胎技术

Rolling Resistance Basic Foundation

Randall CLARK

Rolling Resistance

Basic Foundation

•Definition and Origins

•Relative magnitude

–Cars

–Trucks

–Buses

•External Variables

What is Rolling Resistance

Rolling Resistance •FRR-Tire drag on vehicle montion

How can you fell Rolling Resistance?•If you ride a bicycle with

tires at low pressure,you

have to work harder to

overcome the increased

rolling resistance.

So is it Energy or Force?

Both!

•Rolling Resistence

–=tire rolling energy consumed per unit distance –=work/distance

–=[Newstons x meters]/msters

•Rolling Resistance

–=resistance force of the tires

–=force

–=Newtons

What causes Rolling Resistance?•The main three physical causes of rolling resistance

Where is most of the energy

consumed in the tire?•Computer Modeling of Energy Loss

The Role of Rubber Compounds

•Positive: provide grip, resilience, toughness, wear •Negative: waste heat generated when tire flexes; lost energy comes form fuel tank

Choosing Rubber Compounds •There are rubber compounds that can redece rolling resistance

•The choice depends on many design requirements:

–wear; grip; cut resistance….

•Some new high tech compounds can reduce rolling resistance with few compromises

Tread Pattern Effects

examples: truck tires

Lower Rolling Resistance

Smooth rib tires Higher Rolling Resistance lug tires

Choice of Rubber Compounds & Tread Patterns affect Rolling Resistance & Heat Generation

Truck tire images taken with infrared camera while tire rolling;

both tires running under identical load and pressure

Comparing low rolling resistance

to high rolling resistance

•You can see the difference in tread pattern and compound

By placing different

brands/types of tires

on similar positions

on the vehicle, you

can see the heat and

therefore RR

differences by using

an infrared camera at

night…

Cooler tires have other benefits, also •Truck tires: tire carcass lasts longer for potential retreading

–Better use of reources

•Car tires: cooler tires reduce chance of failure while running

–safety

Doses the tire structure play a role?

Yes! Radial tires are better

The Bias-ply Tire •A casing made of

several plies positioned

in a criss-cross manner

The bias-ply tire

HIGH FRICTION=HIGH ROLLING RESISTANCE Bias tire: Crown and sidewalls interdependent •Sidewall flesing is transmitted to

the tread resulting in:

–Distortion of ground contact area

–Scissoring of casing plies that

leads to overheating

–High friction with the road surface