One of parameters of the adjusted engine – extent of compression. The size of this indicator is closely connected with the power, detonation firmness, profitability and other similar characteristics of the engine. So, it is important to calculate extent of compression correctly.
It is required to you
- - calculator;
- - burette;
- - glass;
- - sealant.
Instruction
1. Extent of compression is defined as the relation of full volume of a cylinder of the internal combustion engine to the volume of its combustion chamber. Calculate this indicator by the following formula: CR= (V + C) / C, in which V – the operating capacity of a cylinder, With – combustion chamber volume.
2. To find the capacity of one cylinder, it is necessary to divide the engine capacity (engine capacity) into quantity of cylinders. For example, if the operating volume of the four-cylinder engine is equal to 1200 cubic centimeters, then the capacity of one cylinder will be equal to 300 cubic centimeters.
3. Capacity of the combustion chamber is a volume which remains over the piston when that is in the top dead point. It includes several sizes: cavity volume in a head, dredging volume (in the piston bottom), volume between the top part of the block of the piston and the top part of the block of a cylinder at the time of finding of the piston in the top dead point and also the volume equal to laying thickness.
4. If the used laying round, then the volume equal to its thickness is determined by a formula: Vcc= [(p*D2*L)/4]/1.000, where p=3.142, where L - thickness of the laying which is in the clamped state (in mm), D – diameter of an opening in laying (in mm). If laying not round, then for measurement of volume use the burette. For this purpose paste laying by means of sealant to glass then place glass on a plain surface and fill with water an opening in laying, using for this purpose the burette.
5. Knowing the operating capacity of a cylinder and volume of the combustion chamber, substitute these values in a formula and calculate extent of compression.
6. The thermal efficiency is directly connected with extent of compression: the extent of compression is higher – the less fuel is used by the engine for obtaining the required power.