Self inflating tyres - Engineering Seminar Report

The mode of transport is one of the most important criterions these days. The vehicles safety is thus essential. Accidents are also increasing at a quick pace. There are several factors which causes these accidents. The improper inflation of tyres is one among them. Tyres lose air through normal driving (especially after hitting pot holes or curbs), permeation and seasonal changes in temperature. When tyres are under inflated, the tread wears more quickly. Under inflated tyres get damaged quickly due to overheating as compared to properly inflated tyres. The under inflation also causes a small depreciation in the mileage as well. Above all the vehicles running with under inflated tyres can cause accidents.

              Thus to rectify all these defects we are using self inflating systems. The pressure monitoring systems in such systems helps in monitoring the tyre pressure constantly. The system which contains sensors feed the information to a display panel which the driver can operate manually. The electronic unit controls all the information. The source of air is taken from the vehicles air braking system or from the pneumatic systems. Thus it helps in re-inflation of the tyres to proper pressure conditions. 

How Tyres Work

              If you're in the market for new tyres, all of the variables in tyre specifications and the confusing jargon you might hear from tyre salesmen or "experts" might make your purchase rather stressful. Or maybe you just want to fully understand the tyres you already have, the concepts at work, the significance of all of those sidewall markings. What does all this stuff mean in regular terms?

              In this article, we will explore how tyres are built and see what's in a tyre. We'll find out what all the numbers and markings on the sidewall of a tyre mean, and we'll decipher some of that tyre jargon. By the end of this article, you'll understand how a tyre supports your car, and you'll know why heat can build up in your tyres, especially if the pressure is low. You'll also be able to adjust your tyre pressure correctly and diagnose some common tyre problems!

Tyre-inflation Basics

About 80 percent of the cars on the road are driving with one or more tyres underinflated. Tyres lose air through normal driving (especially after hitting pot holes or curbs), permeation and seasonal changes in temperature. They can lose one or two psi (pounds per square inch) each month in the winter and even more in the summer. And, you can't tell if they're properly inflated just by looking at them. You have to use a tyre-pressure guage. Not only is underinflation bad for your tyres, but it's also bad for your gas mileage, affects the way your car handles and is generally unsafe.

Self-inflating Systems 

Tyre-inflation systems have three general goals:

·          Detect when the air pressure in a particular tyre has dropped - This means they have to constantly (or intermittently) monitor the air pressure in each tyre.

·          Notify the driver of the problem

·          Inflate that tyre back to the proper level - This means there has to be an air supply as well as a check valve that opens only when needed.

Parts of Any Self-inflating System

              While the available tyre inflation systems vary in design, they share some common elements.

·        They all use some type of valve to isolate individual tyres to prevent airflow from all tyres when one is being checked or inflated.

·        They have a method for sensing the tyre pressures. This is addressed in most cases with central sensors that relay information to an electronic control unit and then to the driver.

·    They have an air source, which is usually an existing onboard source such as braking or pneumatic systems. When using an existing system, however, they have to ensure that they don't jeopardize its original function. For this reason, there are safety checks to ensure that there is enough air pressure for the source's primary use before pulling air for tyre inflation.

·        There has to be a way to get the air from the air source to the tyres, which is usually through the axle. Systems either use a sealed-hub axle with a hose from the hub to the tyre valve or else they run tubes through the axle with the axle acting as a conduit.

·        There has to be a pressure relief vent to vent air from the tyre without risking damage to the hub or rear-axle seals.

  

Central Tyre Inflation System (CTIS)

               The idea behind the CTIS is to provide control over the air pressure in each tyre as a way to improve performance on different surfaces. For example, lowering the air pressure in a tyre creates a larger area of contact between the tyre and the ground and makes driving on softer ground much easier. It also does less damage to the surface. This is important on work sites and in agricultural fields. By giving the driver direct control over the air pressure in each tyre, maneuverability is greatly improved.