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[harsh]

What is 4 valve DTSi engine used in newly launched pulsar 135

[Andresebastien]

harsh, on 13 January 2010 - 03:19 PM, said:

What is 4 valve DTSi engine used in newly launched pulsar 135

Current motorcycle and scooter engines have a single spark plug that ignites the air and fuel mixture inside the combustion chamber. As a result, the rectangular combustion chambers in most motorcycle engines have a certain degree of unburnt air-fuel mix, since the flame front arising from the sparkplug does not reach all the corners of the combustion chamber.

This loss of unburnt air-fuel mix leads to lower power and fuel efficiency. After Bajaj Auto perfected the technology for adding a second spark plug to the engine and the engine management systems to go with it, it decided to first put the new technology to work on the Pulsar.

What is DTSi?

The DTSi (Digital Twin Spark ignition) technology from Bajaj could potentially revolutionise motorcycling in the country. The company may well want to replicate the technology in its other engines as well. This technology, which is also being patented by Bajaj Auto, boosts the performance of the engine, while simultaneously cutting emissions.

The DTSi technology incorporates twin sparkplugs at either ends of the combustion chamber for faster and better combustion. Single sparkplug meant slower burning of the air-fuel mixture and sub-optimal combustion chamber characteristics. This is the heart of the new technology from Bajaj. But, its benefits are fully realised only after it is combined with a computerised direct ignition (CDI) system and new generation throttle response system.

The digital CDI in the new Pulsar, which features an advanced eight-bit microprocessor handles the spark delivery. The programmed chip's memory contains the optimum ignition timing for any given engine rpm, thereby squeezing out the best performance characteristics from the combustion chamber. Working together with the Throttle Responsive Ignition Control System (TRICS III) supposedly also delivers the optimum ignition timing for varying load conditions.

Bajaj has also developed a new third generation TRICS III to complement the new ignition system. The TRICS system controls the ignition based on throttle use. Depending on the needs of the motorcycle rider, whether for cruising or a burst of acceleration (such as for overtaking), the ignition requirements changes; especially useful in city riding conditions.

Based on the level of throttle opened, a magnetic field opens or closes the reed switch, which, in turn, is connected to the Digital CDI. The CDI then switches to the desired Ignition Advance Timing Maps (pre-programmed timing from the eight-bit processor). This helps the engine achieve an ideal ignition spark advance for every throttle opening and engine rpm level.

[Saurabh Sharma]

grt reply boss!
Another thing that Bajaj has brought is "Exhautec". Could you please throw some light on this also?

[meddy90]

sir can you share something about CDI

[Andresebastien]

Capacitor discharge ignition (CDI) or thyristor ignition is a type of automotive electronic ignition system which is widely used in outboard motors, motorcycles, lawn mowers, chain saws, small engines, turbine powered aircraft, and some cars. It was originally developed to overcome the long charging times associated with high inductance coils used in inductive ignition systems, making the ignition system more suitable for high engine speeds (for small engines, racing engines and rotary piston engines). Capacitor discharge ignition uses capacitor discharge current output to fire the spark plugs.

The basic principle

Most ignition systems used in cars are inductive ignition systems, which are solely relying on the electric inductance at the coil to produce high-voltage electricity to the spark plugs as the magnetic field breaks down when the current to the primary coil winding is disconnected (disruptive discharge). In a CDI system, a charging circuit charges a high voltage capacitor, and during the ignition point the system stops charging the capacitor, allowing the capacitor to discharge its output to the ignition coil before reaching the spark plug.

A typical CDI module consists of a small transformer, a charging circuit, a triggering circuit and a main capacitor. First, the system voltage is raised up to 400-600 V by a transformer inside the CDI module. Then, the electric current flows to the charging circuit and charges the capacitor. The rectifier inside the charging circuit prevents capacitor discharge before the ignition point. When the triggering circuit receives triggering signals, the triggering circuit stops the operation of the charging circuit, allowing the capacitor to discharge its output rapidly to the low inductance ignition coil, which increase the 400-600 V capacitor discharge to up to 40 kV at the secondary winding at the spark plug. When there's no triggering signal, the charging circuit is re-connected to charge back the capacitor.

The amount of energy the CDI system can store for the generation of a spark is dependent on the voltage and capacitance of the capacitors used, but usually it's around 50 mJ, or more. The standard points, coil, distributor ignition, more properly called the Kettering ignition system, produces 25mJ at low speed and drops off quickly as speed increases.

Most CDI modules are generally of two types:

* AC-CDI - The AC-CDI module obtains its electricity source solely from the alternating current produced by the alternator. The AC-CDI system is the most basic CDI system which is widely used in small engines.

Note that not all small engine ignition systems are CDI. Some older engines, and engines like older Briggs and Stratton use magneto ignition. The entire ignition system, coil and points, are under the magnetized flywheel.

Another sort of ignition system commonly used on small off-road motorcycles in the 1960s and 1970's was called Energy Transfer. A coil under the flywheel generated a strong DC current pulse as the flywheel magnet moved over it. This DC current flowed through a wire to an ignition coil mounted outside of the engine. The points sometimes were under the flywheel for two-stroke engines, and commonly on the camshaft for four-stroke engines. This system worked like all Kettering (points/coil) ignition systems... the opening points trigger the collapse of the magnetic field in the ignition coil, producing a high voltage pulse which flows through the spark plug wire to the spark plug.

If the engine was rotated while examining the wave-form output of the coil with an oscilloscope, it would appear to be AC. But you must consider that since the charge-time of the coil corresponds to much less than a full revolution of the crank, the coil really 'sees' only DC current for charging the external ignition coil.

Some electronic ignition systems exist that are not CDI. These systems use a transistor to switch the charging current to the coil off and on at the appropriate times. This eliminated the problem of burned and worn points, and provided a hotter spark because of the faster voltage rise and collapse time in the ignition coil.

* DC-CDI - The DC-CDI module is powered by the battery, and therefore an additional DC/AC inverter circuit is included in the CDI module to raise the 12 V DC to 400-600 V DC, making the CDI module slightly larger. However, vehicles that use DC-CDI systems have more precise ignition timing and the engine can be started more easily when cold.

[Andresebastien]

ExhausTEC stands for Exhaust Torque Expansion Chamber, a technology patented by Bajaj.

The technology involves use of a small chamber connected to the exhaust pipe of the

engine to modify the back-pressure and the swirl characteristics, with an aim to

improve the low-end performance of the bikes. The ExhausTEC technology is claimed to be

highly effective in improving the low- and mid-range torque.



What does this Torque Expansion Chamber do?

We should first have an idea of what “Torque” is and what it does to a motorcycle.

Torque is the “twisting force” that rotates the wheels of a motorcycle.

It is torque which is responsible for moving/accelerating at slow speeds. More torque

at slow speeds means that acceleration or pick up at slow speed will be good.

The Torque Expansion Chamber (TEC) improves the scavenging (exit process) of the

exhaust gases and is also designed create a pressure difference inside the exhaust

pipe. This pressure difference inside the exhaust pipe creates a vacuum which helps to

pull in additional air-fuel mixture at low engine speeds and thus improves the engine

torque at low revs without compromising the mid or high engine revs.
The benefit of the feature is that good pick up is available right down from slow

engine speeds and therefore there is less need for changing gears in stop-go traffic

conditions.

[Kittu Coffybite]

sir am very glad to read this.. can u say about that when an engine is running the mechanical energy produced can be converted in to electrical energy n stored n this energy is used to run the vehicle so that the fuel can be saved.. is it possible to do so.. will please suggest me in dis... waiting for ur reply sir...