VOLKSWAGEN TDI TECHNOLOGY EXPLAINED !!

Turbocharged direct injection engine is invented by Volkswagen group. TDI identifies all advanced diesel engines using direct fuel injection and a turbocharger. TDI engines are economical and smooth with high levels of torque and good energy efficiency.

Working of TDI

Fuel needs oxygen to burn and the engine has to be supplied with huge quantities of air to get enough. You can solve this problem with a bigger engine - or you can solve it with a turbocharger - as in the TDI. Driven by the exhaust gases, it squeezes air more tightly into the cylinders.

After being drawn through the turbocharger the air is then cooled by passing it through an intercooler, before entering the combustion chamber where diesel is injected directly into the cylinders at very high pressure through a nozzle. It's this intensive mixing of highly atomized fuel with the cooled compressed air that leads to better, more efficient combustion.

Your driving experience is quiet and refined because effective sound keeps noise to a minimum, while hydraulic engine ensure smooth, low-vibration running.

KNOW WHY ROYAL ENFIELD MAKES THUMP LIKE SOUND !!

 It is mainly because of the heavy push-rods and long stroke (86 to 90mm) of the RE engine. At low RPMs, the RE engine takes almost half a second to complete one stroke, making the exhaust stage last much longer than usual. The fuel-air mixture that explodes during combustion stroke increases the pressure inside the cylinder much higher than a 150cc engine. So during exhaust when the exhaust valve opens, the gases rush out in an explosive blast, producing the thump.

The reason it has a large pushrod and long stroke is because the engine displacement for this bike is 350 cc in a lean-burn single cylinder. Very few bike makers across the world use a single cylinder for an engine displacement as big as 350cc or even 500cc. This is because such an engine develops a slow revving or thumping characteristic which is contrary to what one would typically find in sport bikes, which in one twist of the throttle vrooms up to 10-12,000 rpm while if you twist the throttle of a Royal Enfield you will realize it will thump its way to max 4-5000 RPM. Long-stroke engines produce high torque at low RPM but less power at max rpm. Short-stroke engines produce low torque at low RPM but more power at max rpm.

ANTI-LOCK BRAKING SYSTEM EXPLAINED !!

Requirement of ABS Technology:

We know that when we apply brake, it pushes the brake pad on running drum or disk. For heavy loaded vehicle we need to high braking force to stop of slow down the vehicle. This braking force generate by some means like hydraulic pressure, Air pressure etc. When the vehicle is running and we want to stop the vehicle we push the brake pedal. Due to excessive braking causes skidding. This skidding jam the wheel but due to inertia the vehicle tends to skid on the road and it became out of control from driver. This is called locking of the wheel.

This is understood by that when we run on the floor and eventually tends to stop we slip down on it. This is exactly true for the vehicle. This type of locking is harmful for driving and may cause accident. So we have to remove it use of a new safety system. This system is called ABS.

Working of ABS Technology:

We have been already explained how locking of road wheels due to excessive braking causes skidding. Modern antilock brake systems not only cause the vehicle to stop without deviating from its straight line path, these also provide directional stability since there is no skidding of the wheels.

Skidding is avoided by releasing the braking pressure just before the wheels lock up, and then reapplying the same. These releasing and reapplying the brakes in succession is what an antilock system does and this process is called pressure modulation. This system can modulate the pressure to the brakes about 15 times per second.  The feel of brake pedal in case of ABS equipped brakes is quite similar to that of conventional power brake system.

An ABS consist of an electronic control unit, one sensor on each wheel, an electrically driven hydraulic pump and a pressure accumulator. Accumulator is used to store hydraulic fluid to maintain high pressure in the braking system and to provide residual pressure for power assisted braking. ECU monitors and controls the antilock function when required. Its function is based on inputs from the wheel speed sensors and feedback from the hydraulic unit to determine whether the ABS is operating precisely and also to decide when the antilock operation is required. In some antilock braking system, a lateral acceleration sensor is also provided to monitor the side movement of the vehicle while taking a turn. This ensures proper braking during turns also.

When the front wheels of vehicle are locked, its maneuverability is reduced, whereas in case of rear wheel locking, the vehicle stability is reduced. ABS calculates the required slip rate of the wheels accurately based on the vehicle speed and the speed of the wheels and then controls the brake fluid pressure to achieve the target slip rate. Although ABS prevents complete locking of the wheel.

ABS is manufactured by Bendix, Delco Moraine, Kelsey-Hayes Lucas Girling, Bosch etc.