16-07-2012, 03:53 PM
COMBUSTION CHAMBER FOR CI ENGINES
COMBUSTION CHAMBER FOR CI ENGINES 2222.ppt (Size: 1.33 MB / Downloads: 84)
INTRODUCTION
The important function of CI engine Cc is to provide proper mixing of fuel and air in short time.
In order to achieve this an organized air movmt called swirl is provided, high relative velocity b/w the fuel droplets.
DIRECT INJECTION CHAMBER
Its also called as open Cc.
The entire volume of Cc is located in the main cylinder and the fuel is injected into this volume.
The injector nozzle used for this type of chamber are generally of multi hole type working at relatively high pressure ie above 200bar.
Some of the DI types of chambers are,
Shallow depth chamber
Hemispherical chamber
Cylindrical chamber
Toroidal chamber
SQUISH: It is the rapid ejection of gas trapped b/w the piston and some flat or corresponding surface in the cylinder head.
Advantages
Minimum heat loss during compression because of lower surface area.
No cold starting problems.
Fine automation because of multi hole nozzle.
Disadvantages
High fuel injection pressure reqrd and hence complex design of fuel injection pump.
Accurate metering of fuel by the injection system particularly for small engines.
INDIRECT INJECTION CHAMBER
Its also known as DIVIDED Cc.
Here the combstn space is divided into two or more distinct compartments connected by restricted passages.
This creates considerable difference in pressure b/w them during combstn process.
Advantages
Injection pressure reqrd is low.
Direction of spraying is not important.