engine is the most critical part of the car is the most important factor in determining the performance of the car, like a human heart. Most people know that our daily use of a piston reciprocating engine, divided into two-stroke engines and four-stroke engines (the four-stroke engine, for example), but there is a majority of people are not as well-known engine, that is the rotary engine, also known as the Wankel engine.
we often see daily in the form of a reciprocating motion of the piston engine, i.e. a piston reciprocating linear motion in the cylinder, a crankshaft by the linear motion of the piston into rotation of the crankshaft and the rotor of the engine without this conversion process, which is driven by the engine to the main shaft by rotation of the piston within the cylinder (i.e., the engine crankshaft is common, because it is not curved no longer called the crankshaft) rotates, so that the two have a big difference.
through the engine combustion air mixture to push the piston reciprocates to drive the crankshaft, the piston top surface furthest from the center line position of the crankshaft referred to the top dead center (TDC — Top Dead Center), the piston crown a position closest to the surface from the centreline of the crankshaft referred to the bottom dead center (BDC — Bottom dead Center). in a four-stroke gasoline engine, for example, as shown
a feed induction stroke: the piston moves from the top dead point to the bottom dead center is called during the intake stroke (crank rotation angle 0 ~ 180deg;), the stroke of the intake valve opening, exhaust valve closing, the air chamber and the atmosphere, atmospheric pressure so that oil and gas mixture into the intake end of the cylinder pressure is about 0.075 ~ 0.09MPa.
b of the compression stroke: the piston from the bottom dead point to the top dead center during the compression stroke is called (crankshaft rotation angle 180deg; ~ 360deg;), the stroke of the intake and exhaust valves fully closed, the indoor air mixture gas pressure is gradually increased, the end of the compression stroke air chamber pressure is about 0.6 ~ 1.2MPa.
c power stroke: the piston moves from the top dead point to the bottom dead center is called during the power stroke (crankshaft rotation angle 360deg; ~ 540deg;), the stroke of the intake and exhaust valves fully closed, the piston when the spark ignition top dead center position of spark plug air mixture in the cylinder pressure dramatically increased (up to 3 ~ 5MPa), to push the piston for the songMovement of the shaft, the pressure gradually decreases, the power stroke end of the air chamber pressure is about 0.3 ~ 0.5MPa.
d exhaust stroke: the piston from the lower dead point is called the top dead center during the exhaust stroke (crank rotation angle 540deg; ~ 720deg;), the intake valve closing stroke, the exhaust valve opens, the upward movement of the push piston combustion exhaust gas after the exhaust gas chamber, the end of the stroke of the gas chamber pressure is about 0.105 ~ 0.115MPa. The end of the stroke of this engine also marks the end of a work cycle.
“rotary engine”
The figure below shows comparative rotor of each engine stroke reciprocating engine (two on the left side in FIG an intake hole, right exhaust gas), the same as with the reciprocating rotary engine four-stroke engine working cycle, i.e., the intake, compression, for power, exhaust four stroke configuration, FIG arc BC by a triangular cylinder type rotor the working chamber (BC working chamber) is formed between the surface to illustrate the working principle of the four-stroke rotary engine.
abcda
of the intake stroke: When the angle C to the triangular top rotor into the right-hand edge of the hole, BC starts the intake working chamber, in position a, the intake vent communicating, intake and exhaust overlap. This is the minimum volume of the working chamber BC, corresponding to the reciprocating engine top dead center position. As the rotor continues to rotate, the volume of the working chamber increases gradually BC, the combustible mixture is continuously drawn into the cylinder. When the rotor rotation 90deg; (270deg ;, spindle speed and spindle speed ratio of the rotor rotary engine of 1: 3, is determined by the gear intermeshing) reaches the position B, BC working chamber volume reaches a maximum, corresponding to the reciprocating engine dead center position, the intake stroke ends.
Compression stroke: As the cam continues to rotate the rotor, beyond the angle B into the top left edge of the hole, the compression stroke begins, the volume of the working chamber is gradually reduced BC, increasing pressure to reach the position c when the rotor rotation 180deg; (spindle 540deg;), BC minimum working chamber volume, corresponding to the top dead center position of the reciprocating engine, the compression stroke ends.
power stroke: the end of the compression stroke, spark plug arcing, high temperature and pressureTriangular gases push the piston continues to rotate, the volume of the working chamber is gradually increased BC, when C reaches the top corner edge of the right side of the vent, 270deg in position d, the rotation of the rotor; (spindle 810deg;), the volume of the working chamber reaches the maximum BC , corresponding to the reciprocating engine bottom dead center position, the end of the power stroke.
exhaust stroke: C triangular top rotor angular rotated position of the right side of the exhaust hole, an exhaust stroke begins, the final triangle rotor returns to the position a, the end of the exhaust stroke, the rotor rotation 360deg; (spindle speed three weeks), the end of a work cycle. Meanwhile, CA working chamber, AB working chamber were also complete a cycle.
● comparison engine configured:
The rotary engine: Body group, valve means, supply system, ignition system, cooling system, lubrication system, the system starts
reciprocating piston engine: body group, a crank link mechanism, valve means, supply system, ignition system, cooling system, lubrication system, boot the system
● two engine advantages and disadvantages:
◆ reciprocally engine:
advantages:
1. the manufacturing technology is mature, has been the birth of 120 years, a variety of technology continues to improve, is the world’s most widely used internal combustion engine, low maintenance cost.
2. reliable, good air tightness and reliability of power transfer.
3. Good fuel economy.
Disadvantages:
1. The complicated structure, large size and heavy weight.
2. The crank and connecting rod mechanism the reciprocating inertia force and moment of inertia caused by the reciprocation of the pistons can not be completely balanced, and the magnitude of this inertial force is proportional to the square of the rotational speed, so that the smoothness of the engine decrease, limiting the development of high engine speed.
3. Since a four-stroke reciprocating piston engine operating mode is four stroke cycle entirely on three rotating flywheel inertia, resulting in power, torque output of the engine is very uneven, although modern engine uses multiple V-shaped cylinder arrangement and to reduce this drawback, but can not be completely eliminated.
The rotary engine ◆:
Advantages:
1. small size, light weight, easy to reduce the center of gravity of the vehicle. Since the rotor of the engine without crank and connecting rod mechanism, the height of the engine is greatly reduced, while reducing the vehicle center of gravity.
2. Simple. Compared to a reciprocating piston engine, rotary engine crank linkage reduced, resulting in a greatly simplified means of the engine, reduced parts.
3. The uniform torque characteristics. Since the rotor while the engine has a three cylinder working chamber in the operating state, the output torque is more uniform compared to reciprocating piston engines.
4. The high-speed conducive to the development of the engine, the piston and the rotor spindle rotation speed ratio of 1: 3, so that the piston does not need a high speed to achieve a high engine speed.
Disadvantages:
High
1. The fuel consumption, emissions compliance is difficult. Each cylinder has its three working chambers, the piston per rotation of the rotor corresponds to three of the power stroke, and a reciprocating piston engine at 3000rpm for comparison, a reciprocating piston engine injector 750 beats / min, rotor speed corresponds to the engine 1000 rpm for, but requires injection 3000 times / min, fuel consumption is significantly higher than that seen rotary engine reciprocating piston engine, while the shape of the rotor combustion chamber of the engine to the full combustion of the combustible gas mixture, the flame propagation path is long, the fuel oil consumption, which leads to higher levels of pollutants in the exhaust gas.
2. The structure of the engine can cause the ignition to take a compression ignition can not be employed, i.e., not only can be used as a fuel with gasoline and diesel.
Since the rotor 3. The eccentric shaft of the engine, resulting in greater engine vibration.
4. The high power output shaft (spindle) position, the vehicle is not conducive disposed.
High manufacturing techniques
The rotary engine, relatively high cost.