1. Classification engine layout
1) a front-engine
Front engine, i.e., before the engine shaft before the bit. Front engine advantage of simplifying the structure of the car is the transmission and the drive axle, particularly for currently mainstream absolute front-wheel drive vehicle, the engine delivers power directly to the front wheels, a long shaft is omitted, only reducing power transmission loss, but also greatly reduces the complexity of the failure rate and the power transmission mechanism. In addition, the front of the engine driver’s home, in the event of a frontal collision, the engine can protect the driver from impact, thereby enhancing the safety of the car. Between the longitudinal axis
2) mid-engine
is set in the engine, i.e. an engine of the vehicle, generally before or after the engine is located in the cockpit. So to speak, mid-engine rear-wheel drive car is definitely or four-wheel drive.
car when cornering, the various parts of cars because of inertia are moved to the outside bend, the engine is the largest mass portion, due to inertia of the engine with a steering force to the vehicle body in the closed to the bending important influence. Mid-engine vehicle inertia feature is the largest in the center of the vehicle body of the engine, so that the body weight distribution can be made close to the ideal equilibrium state. Generally, only those super sports car or a sports car driving pleasure stress only mid-engined
Of course, the mid-engine also has disadvantages, since the mid-engine, resulting in a narrow cabin, the seat can not be arranged more, Further, since the from occupants too close to the engine, thus noisy. However, only the pursuit of automobile driving performance of people, these are no longer peace, and even some people prefer to hear the roar of the engine roaring.
3) rear engine
In general, the most pure engine rear engine is arranged behind the rear axle, it is the most representativeBus, and then a handful of mid-engine passenger cars, the most representative is the Porsche 911, of course, but also smart rear engine.
was a classic Volkswagen Beetle and Fiat 126P model is a rear-engine
4) transverse engine [123 ]
parallel to the transverse engine refers to an engine and automotive front axle. Simply say that you stand in front of the front of the engine, if the engine sideways in front of you, that is transverse engine
In general, the precursor of the compact car, the majority of mid-size sedan and limousine are few using a transverse engine layout.
Advantages:
transverse crankshaft of the engine, the transmission and the axle input and output shaft are parallel, so that if a front-drive, it is most appropriate that the front transverse engine, the power short transmission distance, in the same direction, and therefore higher transmission efficiency.
On the other hand, due to the small longitudinal space occupied by the transverse engine, can greatly shorten the longitudinal extent of the space in the engine compartment, the result is large driving space, in particular a front passenger leg portion expand the space. This is especially important for the limited size of the compact car in terms.
Disadvantages:
before and after the imbalance in the weight distribution of the maximum defect of transverse engine, since the input shaft parallel to the transverse engine crankshaft of the engine gearbox coupled together, it may be arranged before the engine front axle, but the heaviest parts by weight of automobiles all concentrated in front of the front axle load is too large makes so prone understeering situation, the top-heavy front and rear axle weight vehicle will enable high-speed cornering the rear end of the lack of stress, some irrational distribution of axle load transverse engine cars and even up to 30 percentage percentage after the first 70, its performance can be imagined.
On the other hand, due to the transmission side of the transverse engine installation position biased too, a long drive shaft is a short, when a great driving force acting on the drive shaft of unequal length, there are two front wheels make the car speed difference, resulting in hard acceleration when the front left and right swing phenomenon, that is, we often say that the torque steer, which is particularly evident in the large displacement of FF models.
5) longitudinal engine
refers to a vertical longitudinal engine automobile engine and front axle, simply say that you stand in front of the front of the engine, if the engine is placed vertically in front of you, that is a longitudinal engine.
Generally after driving a longitudinal engine are used, because the power to be transferred to the rear axle, in a case where the transmission distance can not be shortened, it is necessary to reduce as much as possible the power conversion directions. If then tapped, because the vertical direction of the crankshaft and the drive shaft, so first converting a direction to transmit power through the shaft, the shaft and the direction is perpendicular to the rear axle, the rear axle is required then conversion over the direction of rotation, which undoubtedly reduces the efficiency of the transmission system. The use of such longitudinal engine crankshaft and the transmission shaft can be parallel, reducing the drive direction conversion undoubtedly reduces the loss of energy.
On the other hand allows the longitudinal engine position of the transmission back extension as far as possible, the center of gravity of the power train located behind the front axle, the vehicle body weight would allow more evenly.
in the longitudinal engine platform, there is a more specific example, the use of which is longitudinally mounted engine front-drive Audi. Although Audi longitudinal engine using more traditional this is to take care quattro, but longitudinally mounted engine front-drive layout engine can also bring a good front-rear weight ratio. Such an arrangement may be disposed before the engine longitudinal front axle, gearbox and engine directly connected to the engine compartment space will be limited, it is necessary arranged behind the front axle, the input shaft of the gearbox and the engine crankshaft rotation around the same axis , to bear the weight of the engine and gearbox of the vehicle front axle, he like the balance point, the engine and gearbox located in front and rear sides of the front axle, so that the engine and gearbox front bearing weight more evenly distributed the center of gravity ratio is more reasonable, although they are still before the drive will Tuitou phenomenon, but its weight ratio is much better than ordinary transverse engine models such as the Audi A4 before and after the precursor of the weight ratio reached a more perfect 55:45.
However longitudinal engine also has disadvantages, since the vertical position causing the engine nacelle take a long space, resulting in some loss of the driving space.
6) Anti-engine
“inverted” is tapped fatA special arrangement mover, usually a front transverse engine exhaust manifold, in the arrangement of the intake manifold, simply means “before the backward”, if the transposition into the exhaust gas, the the intake manifold to the front, rear manifold placed into “forward after the” so-called “inverted” a. Only transverse engine only say “pros and cons of home”, the longitudinal engine intake and exhaust manifolds on left and right ends, interchangeable and there is no difference, so there is no such argument. Use of anti-engined around our car a lot, Ford Focus, Mondeo, used on the Mazda, Lancer wing of God, and the new Regal 2.4 and other models are anti-mounted engine
advantage inverted engine wherein the intake manifold at the windward side, and better able to reduce the intake air temperature, the temperature drop of the air density is increased, the oxygen content per unit volume are increasing, it is possible to make the combustion more fully, to improve efficiency, reduce fuel consumption . For non-direct injection engine, is arranged such that the trans-mounted supply line but also with the intake manifold is moved to the front of the tube, it has a better cooling effect. After shifting the design of the exhaust manifold, the exhaust pipe is no longer pass under the engine, the engine can be shifted downward position, the effective center of gravity to enhance handling performance, and further with an exhaust pipe from the engine, the cooling system to reduce thermal load, avoiding the impact on the oil pan, exhaust gas, no “twists” the conduit so that exhaust resistance is greatly reduced, the exhaust gas smoother, more efficient, the engine can be output at high speed higher power .
However, the engine is not perfect inverted, after the first exhaust pipe so as to shift the position closer to the passenger compartment, and the high-temperature exhaust noise easily penetrate into the passenger compartment, the temperature in order to reduce the influence of noise and , you need to spend more of the cost of doing handle noise insulation in the firewall and other locations. Another disadvantage is inverted smooth engine exhaust line is reduced back pressure in the exhaust pipe, so that the reduction in exhaust efficiency of the engine speed is low, thereby affecting the efficiency of the intake air, the intake air-fuel mixture in the intake manifold is often the case can not be completely sucked into the cylinder, are likely to cause uneven density of mixed gas, insufficient fuel combustion, etc., without adsorbed into the cylinder on the intake valve and the wall of the small droplets can accumulate easily formed under high temperature environment carbon. That is why generally inverted engine power output at low speeds weaker, but also many engine models using inverted prone to carbon deposition mainlyOne of the factors.
However, with the variable-length intake manifold and the current mainstream variable valve timing technologies, applications, engines inverted vulnerable are gradually emerging direct injection technology is being gradually improved. Variable valve timing techniques so that the “gas flow valve and switch” to significantly reduce the adverse effects of mixture concentration of conventional multi-point fuel injection engine, and the application of the direct injection valve switching further weakens the manifold and gas flow of the mixed gas concentration adverse effects of fuel directly into the cylinder, capable of more accurate calculation and control the amount of fuel injection, compared to the outer-cylinder injector reduces the loss of fuel, to improve efficiency and reduce fuel consumption purposes. It can be said, the engine inverted vulnerable in this regard has been effectively compensate, higher efficiency can be achieved in the whole section of the rotational speed, and better characteristics which exert a high speed output.