L is the total evaluation of the power cylinder capacity utilization of the available power from the engine to the angle. The larger the value or power, the higher the degree of enhancement of the engine, an engine emits a certain size smaller effective power. Therefore, to continuously improve Pme (mean effective pressure) and (speed) level n to get more intensive, more lightweight and compact engine, the internal combustion engine has been dedicated to workers in order to goal, therefore liter engine power is the assessment of a whole one of the important indicators of machine performance and enhanced power levels.
1 liter power basic introduction
liter engine power level of quality reflects mainly to see the power and economy, that is to have a good engine power, good acceleration and a more low fuel consumption. Factors affecting engine power and fuel consumption, many of them have the biggest factor affecting the displacement, compression ratio, valve train. But this is only refers terms. DETAILED comparison to the engine, due to differences in the use, design, materials and manufacturing processes, often resulting in significant differences.
There are some large displacement engine power is not necessarily smaller than the displacement of the engine power, for example, to compare the displacement, the vehicle A is 2.0 liter engine maximum power of 97 kilowatts, 2.2-liter engine car B may be the maximum power of 79 kilowatts. Similarly, some of the same car emissions, the same 2.0-liter engine but the output power is not the same. Therefore, it creates a measure called or power.
In the crankshaft of the engine power output based on said effective index indicator, which indicator indicates the level of overall engine performance. Effective indicators include effective power, effective torque, or power and the like. Generally thought, power and torque of these two indicators will reflect the merits of the engine, it is not. Power and torque than the larger the engine, the better, truly reflect the engine’s power indicator is the power emitted per liter of cylinder capacity, that is, or power.
2. Or power defined
or power (kW / L) is defined as the nominal power condition, the engine liter cylinder capacity emitted. Expression or power as:
PL = Pe / iVs
wherein, Pe engine rated power (kW); i is the number of cylinders; Vs of the working volume of the cylinder (L). Further, PL = Pme · n / 30t. Wherein, Pme average effective pressure rated operating conditions (MPa); n is the rated speed (r / min).
3. Measures to improve or power
l represents the power cylinder capacity utilization of the unit, or power unit said that the greater cylinder capacity power emitted. Then, when the engine power is constant, the greater the weight efficiency or power of the engine is higher, relatively smaller engine, the more it saves material. Quality engine design and manufacture of high and low rise reflected power. Since the size or power of the cylinder is mainly determined by the product of the mean effective pressure and speed. L will increase the power increase from the start cylinder pressure and speed, thus increasing the power of the specific measures liters will have:
The pneumatic increase the amount of
This is the first condition of the four-stroke engine to increase the heat, because fuels with air, fuel and air, the latter is more difficult to charge into the cylinder, it is necessary to improve the ventilation conditions, to reduce the intake resistance increases the cross-sectional area of the valve passage, the valve 4 on the use of some form of engine. When the multi-valve structure disposed difficulties, first of all to meet the needs of the intake valve, regardless of how to form a valve arrangement, the number of intake valves is greater than or equal to the number of exhaust gates.
increasing the rotational speed
increasing the rotational speed to increase the amount per unit time of the inflator, car engines are generally high engine speed, rpm 5000 rpm or more.
improve mixing and combustion air mass.
The electronically controlled fuel injection system, the air quality in all conditions to achieve the best possible mixing, place the mixing of air and fuel from the throttle valve to move the nozzle, the fuel sucked directly air mixing, improve the uniformity of the mixture gas essentially.
improving the mechanical efficiency of the engine
to increase the engine output to increase the mechanical efficiency of effective work, mainly to reduce mechanical losses reduce the friction between the parts, the parts related to the processing accuracy, surface quality, lubrication mass, temperature control and reducing accessories.
Here it is noted thatMulti-valve structure and the maximum difference between 2-valve design, is a complex multi-valve gas distribution structure, increasing valves, catheters, camshaft rocker, and some even increased a special camshaft, namely double overhead camshaft (DOHC ), these devices increase the mechanical loss will inevitably increase. Therefore, some manufacturers still pragmatic 2-valve design employed in small and medium automobile engine. These four points are related to each other, for example each cycle of the engine rotational speed the higher the inflator to reduce the problems caused by the more prominent, it is necessary to adopt measures increased passage sectional area of the valve, increase the diameter of the intake valve head or multi-feed valve forms. However, the form of multi-valve will involve problems to the mechanical efficiency of the engine. Things in the world are always contradictions coexist, factory engineers how to adjust the balance, try to improve to deal with conflicts, to reflect on the performance of the various engine.