Monday, March 26, 2012

DTSi Engine


DTS-i

What Is DTS-i......

                               Cut section view of a DTS-i engine
DTSi stands for Digital Twin Spark Ignition. Bajaj developed a few years ago and has incorporated in many of its current engines, takes care of the slow rate of combustion in a simple but novel way. The cylinder head is equipped with two spark plugs, instead of the usual one. By generating two sparks at either ends of the combustion chamber, (approximately 90° to the valve axis) the air-fuel mixture gets ignited in a way that creates two flame fronts and, therefore, a reduction in flame travel of the order of 40 per cent is achieved. A fast rate of combustion is achieved leading to faster rise in pressure. The obvious outcome of this is more torque, better fuel efficiency and lower emissions.

History:-


DTSi stands for Digital Twin Spark Ignition, a Bajaj Auto trademark. Bajaj Auto holds an Indian patent for the DTSi technology. The Alfa Romeo Twin-Spark engines, the BMW F650 Funduro which was sold in India from 1995 to 1997 also had a twin-spark plug technology, and the Rotax motorcycle engines,more recently Honda's iDSI Vehicle engines use a similar arrangement of two spark-plugs. However very few small capacity engines did eventually implement such a scheme in their production prototypes.

Introduction:-

Currently one spark plug at one end of the combustion chamber is the conventional practice. The flame front created by the spark takes some time to reach the farthest portion of the combustion chamber. This leads to slower burning of the Air-fuel mixture and creates limitations in optimizing the combustion chamber characteristics.                       
i.e. Slower combustion rate
      Higher exhaust emission
      Comparatively low mean effective pressure
      High Knocking characteristics etc.
2 spark plugs at either ends of the combustion chamber help in faster and better combustion.
In this technology you will find two spark plugs to ignite the charge in the combustion chamber. Its only in the petrol engine so far and this technology can find a way in disel engine also.

What does the Digital ,Twin ,Spark Ignition means

ü  Digital - Since the spark generation will be initiated by a microchip.
ü  Twin - Since two spark plugs will be used.
ü  Spark ignition - Since the ignition will be done via a spark.
              

     Constructional Detail:-

        The construction of Dts-i engine is same as that of the conventional  4-Stroke engine.                           
         It consist of following parts  Piston
  • Cylinder                                                                    
  • Crankshaft
  • Connecting rod 
  • Fly wheel
  •  Carburator
  •  2-sparkplug 
  •  2-ports 
  •  2-valvs

Here the only change made is that the 2 sparkplug placed at the two opposite end of the combustion chamber At 90 degree to each othor.                     

      Detonation in DTS-i engine....

          In petrol engine major roblem is DETONATION. detonation accurs when the flame travell time from center to the side walls increases the self ignition temp. time. It happens often in the engines having single spark plug.

This is overcome by the DTSi by having 2 spark source on the opposite sides which reduces the flame travel as stated above. Hence no detonation..    

The technology:-

In a conventional single-spark-plug-equipped combustion chamber, and the rate of combustion is relatively slow. The spark plug, usually situated at one end of the combustion chamber, ignites the air-fuel mixture and the ensuing flame spreads like a slowly inflating balloon. There is an inevitable delay for this inflating balloon to reach the furthest part of the combustion chamber. So, there are pockets of poor combustion within the chamber and, overall, the combustion is slow and inefficient.

The Digital Twin Spark–ignition (DTS-i) technology that Bajaj developed a few years ago and has incorporated in many of its current engines, takes care of the slow rate of combustion in a simple but novel way. The cylinder head is equipped with two spark plugs, instead of the usual one. By generating two sparks at either ends of the combustion chamber, (approximately 90° to the valve axis) the air-fuel mixture gets ignited in a way that creates two flame fronts and, therefore, a reduction in flame travel of the order of 40 per cent is achieved. A fast rate of combustion is achieved leading to faster rise in pressure. The obvious outcome of this is more torque, better fuel efficiency and lower emissions.
While that sounds logical and simplistic, TVS Motor claims that the same effect is achieved by employing a single spark plug with differential sparking cycles.   

Working:-

The working of DTS-i engine is very similar to 4-stroke engine but here the only modification done is we are using two spark plug at two ends of the combustion chamber. Which require less time to reach the farthest position of the combustion chamber  and optimize the combustion chamber characteristics.

There are some advance technology used in DTS-i engine which makes it more powerful than the conventional single sparkplug 4-stroke engine like 1.CDI technology 2.Tricks iii technology .

Ignition with a Digital C.D.I.

            A Digital CDI with an 8 bit microprocessor chip handles the spark delivery. The programmed chip’s memory contains an optimum Ignition timing for any given engine rpm, thereby obtaining the best performance characteristics from the combustion chamber. Working together with the TRICSIII system, it delivers Optimum Ignition Timing for varying load conditions.

 TRICS III.
           Throttle Responsive Ignition Control System IIIrd generation. It is a means of controlling the Ignition by operating the Throttle. Depending on the needs of the Rider whether it be cruising, acceleration or max speed, the ignition requirements constantly change. Based on a particular amount of Throttle opening, the Magnetic field generated by the Magnet opens or closes the Reed switch. The Reed switch is connected to the Digital CDI, which signals the CDI to change/switch, the desired Ignition Advance Timing Maps. This helps in achieving a good balance between driveability and Optimum Ignition Spark advance, resulting in an almost perfect Ignition Spark advance for every Throttle opening and Engine rpm.  

Advantage:-

  • Less vibrations and noise
  •  Long life of the engine parts such as piston rings and valve stem.
  • Decrease in the specific fuel consumption
  • No over heating
  •   Gradual increase in the pressure hence power is uniformly distributed throughout the crank angle and hence smooth ride.

Disadvantage:-

  • There is high NOx emission
  •  If one spark plug get damaged then we have to replace both
  • The cost is relatively more
  • You spend double the amount on spark plugs when it is time to replace them.
  

5 comments:

  1. The advantages and dissadvantages contradict each other.1)Advantage no overheating,but dissadvantage says The engine tends to overheat and loose power at higher speeds as compared to a single plug engine.2)Advantage Long life of the engine parts such as piston rings and valve stem.Dissadvantage The engine wear and tear is somehow increased and hence these engines need frequent checkup and overhaul to keep the performance level constant.which one is correct Advantage or Dissadvantage ??

    ReplyDelete
  2. Less vibrations and noise?? Are you sure??

    Long life of the engine parts such as piston rings and valve stem??. Are you sure??

    ReplyDelete
  3. pulsar also dtsi engine,then y its more noise..?

    ReplyDelete