How to explain the basics of automobiles in 60 minutes?

Basic knowledge of automobiles

[Explanation of terms]

MT: Manual transmission ABS: Anti-lock braking system

AT: Automatic transmission EBD: Electronic Brake Force Distribution System

ESP: Electronic Stability Program DSG: Dual Clutch Transmission

CVT: Continuously Variable Transmission DSC: Dynamic Stability Control System

VDC: Vehicle Dynamic Control ETC: Electronic Traction Control System

TCS: All-speed Traction Control System EBA: Emergency Brake Assist System

EDS: Electronic Differential Lock MASR: Traction Anti-Slip Control< /p>

[Engine]

Let’s talk about the most common phenomenon first. Most people think that high horsepower means it must be strong and fast, but at the same time they fail to notice the following problems:

< p>Maximum output power: Generally expressed in horsepower (ps) or kilowatts (kw). The output power of the engine is closely related to the rotational speed. As the rotational speed increases, the output power of the engine will also increase. However, the output power will increase when the rotational speed reaches a certain level. The power will decrease (this may be the opposite of everything, right? Ha!) The maximum output power is usually expressed as r/min, 280ps/7500r/min, which means that it can output a maximum power of 280 horses at 7500 rpm.

< p>Maximum torque: the torque output by the engine. Torque (torque) is generally expressed as N.m/r/min. For example, 100N.m/3000r/min means that the maximum torque of 100N.M can be exerted at 3000 revolutions per minute.

Displacement volume: The working volume of the cylinder refers to the volume swept by the piston from the uppermost end to the lowermost end, that is, the displacement of a single cylinder, which depends on the bore and cylinder stroke (principle V=sh volume formula). The engine displacement Volume is the sum of the displacement of each cylinder.

Number of valves: Valve can be understood literally, it is used for intake and exhaust, of course into the engine. Domestic cars generally use two valves Yes, one intake and one exhaust, which is the most basic configuration. Foreign cars generally use more advanced four-valve, that is, two intake valves and two exhaust valves. This can improve the air intake and exhaust efficiency, and is helpful for increasing engine speed and Power helps a lot. Now some cars have started to use five-valve technology, with 3 air intakes and 2 air outlets. This can increase the air intake and make combustion more complete. But more valves are not necessarily better, because of processing Extremely difficult, the structure is too complex

Cylinder arrangement: Generally speaking, there are in-line, V-shaped, W-shaped (made up of two V's), horizontally opposed, and rotary engines. Different arrangements will also Affects the space occupied and the center of gravity of the car. An in-line 6-cylinder is recommended.

Compression ratio: the ratio of the maximum stroke volume of the cylinder piston to the minimum stroke volume of the cylinder piston. This point is called when the piston in the cylinder moves to the lowest point. is the bottom dead center, and conversely is called the top dead center. Many people like to directly use the direct ratio of the maximum height to the minimum height to obtain the compression ratio. This is actually incorrect because the geometric shape of the cylinder is not necessarily regular and the upper cover is more precise. It is not necessarily a regular plane, so the remaining volume at top dead center cannot be simply calculated based on the ratio of height (compression ratio has a great relationship with the type of gasoline used)

Generally speaking, the horsepower Most of it depends on the engine used:

L4 (in-line four-cylinder)

L5 (in-line five-cylinder)

V6 (V-shaped six-cylinder arrangement)

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L6 (in-line six-cylinder engine, very good performance, only used in high-end cars)

2 Some basic knowledge of cars

V8 (V-shaped arrangement of 8 cylinders)

W8 (W-shaped arrangement of 8 cylinders)

V12 (V-shaped arrangement of 12 cylinders)

W12 (W-shaped arrangement of 12 cylinders)

V16 (V-shaped 16-cylinder engine)

W16 (generally composed of two V8s in parallel, used in very few luxury cars, such as Bugatti)

Horizontally opposed Engine (applied by Porsche and SUBARU)

Rotary engine (applied by Mazda, usually RX type car)

The more cylinders, the higher the horsepower.

The bigger it will be, but at the same time, the most important point should not be ignored, that is, the more cylinders it has, the greater its mass will be, and the occupied space will also increase. The large occupied space further means that the body will be heavier. Larger and further increase in mass. Quality problems will not only affect the car's handling and flexibility, but also affect the car's acceleration performance. Therefore, you must pay attention to the above issues when choosing a car model, and do not blindly see the car's horsepower. To choose, the horsepower of ordinary civilian cars will not exceed 200 horsepower, high-performance sports cars will generally have around 280 horsepower, and top sports cars will have around 500 horsepower or even higher. It should be noted that generally top sports cars will be made of carbon fiber materials. The body, therefore, will reduce the weight to a great extent. Moreover, the interior of the racing car usually has all the interiors that have no practical use removed to achieve the purpose of further reducing the weight. After reading the above rough explanation or choosing a car in the future, you should start to pay attention to it. This is a question.

Torque (torque)

One of the most basic performances of a car. I am afraid that many people who have played racing games will pay more attention to torque than horsepower, right? Torque is indeed a very critical indicator. Torque is the torsional torque generated by the engine. The torque is transmitted from the engine to the vehicle's transmission. Then, with several sets of linked gears in the transmission and differential, the torque is transmitted to the wheel transmission in 1 It will transmit more torque than the 3rd gear when it is in gear, because the 1st gear has the largest transmission ratio in the forward gear. In fact, to put it bluntly, it is the acceleration performance. The acceleration performance of the car often plays a decisive role in the game, just like the general high-end Sports cars will have an indicator released, which is the 0-100km/h acceleration time. Generally speaking, a car that can accelerate in about 4 seconds must be a top-notch car. There are very few cars that can do it in under 3 seconds.

These cars generally have both horsepower and torque.

(Ferrari, Lamborghini, Ford GT, Bugatti, Chrysler, Pagani Zonda, etc. It is said that the EVO 8 MR accelerates from 100 kilometers to 100 kilometers in only 4.3 seconds) Some cars can maximize their torque at low speeds, which means they have good acceleration performance at low speeds. Some cars can exert maximum torque at high speeds. It depends on the model and you need to experience it yourself. The speed at startup is sometimes enough to determine the outcome of a short distance race. And in today's multi-turn track era, the acceleration of the car Performance is more important than outstanding performance. The size of torque is also closely related to the body quality mentioned above. This doesn’t need any more explanation, right?

Therefore, each manufacturer is doing its own thing The car body is made lightweight. Torque can be said to be the source of power. The size of the horsepower also depends on the torque. The basic horsepower of the car can be calculated by combining the torque with the rotation speed. The acceleration ability also depends not only on the torque but also on a The important link is the tires (tires are a very critical equipment of the car, which I will explain in detail later). The important point is that the more cylinders for the same displacement, the better. Of course, there is a limit. As for the smaller the cylinder diameter, the better. Needless to say, the better, the number of cylinders with the same displacement and multiple bores will of course be smaller. (The simplest mathematical volume formula is V = sh, V total = nV) The more detailed the grades, the more detailed the speed grades. , the control feeling will be stronger.

Let’s explain the turbocharging and rotary engines that everyone is more interested in:

Turbocharging technology:

Improve compression The compression ratio is one of the measures to increase engine power, and there are two ways to increase the compression ratio. One is to change the cylinder form (not explained), which is more expensive. The other is our common method of increasing the air intake, turbine Supercharging is to increase the input and output of air.

A turbocharger is actually an air compressor that increases the air intake by compressing air. It uses the inertial impulse of the exhaust gas discharged from the engine. To drive the turbine in the turbine chamber, the turbine drives a coaxial impeller. The impeller pressurizes the air sent from the air filter pipe to pressurize it into the cylinder. When the reaction engine speed increases, the exhaust gas discharge speed and the turbine speed also change. When the speed is increased simultaneously, the impeller compresses more air into the cylinder. The pressure and density of the air increase, which can burn more fuel. Correspondingly, the amount of fuel and engine speed are increased, which can increase the output power.

[Drive]

There are many types of vehicle drive. From my personal understanding, they are divided into the following types:

FF: front-engine front-wheel drive, front-loaded and rear-loaded Light, uneven weight distribution front and rear is not a high-performance driving method

FR: Front-engine rear-wheel drive, good handling and more flexible (detailed introduction later)

4WD : 4-wheel drive, also divided into front and mid-engine, good off-road performance (detailed introduction later)

MR: mid-engine rear-wheel drive, even the F1 drive method is used, no need to say more Did you say it? The performance is ideal and stable.

3 Some basic knowledge about cars

RR: Rear-engine rear-wheel drive, because the weight is concentrated in the rear, it is easy to drift.< /p>

Since FR and 4WD are more commonly used and paid attention to, here is a slightly detailed introduction:

FR: The fastest way to move usually relies on the rear to provide power to generate sprints. The energy provided in the front provides precise control. There is no doubt about this. This is one of the basic laws of physics and geometry. Everyone knows that the movement of a car requires energy, and the large amount of energy required Whether it is acceleration, braking, or steering, energy must be provided and transmitted through the small contact surfaces of the four tires. Each tire will provide a certain amount of grip, and the size of the grip depends on the size of the contact surface. , materials and patterns, as well as the added weight and friction with the road surface. If a certain wheel is providing the energy required for acceleration, then according to energy conservation, the friction provided by this wheel for steering will be reduced at the same time. This situation will cause the steering to be misaligned, that is, if you go too fast when cornering, you will always feel that the car deviates to the outside of the curve (you should feel this way, right? Some racing games do not have this feeling... I won’t give an example) ) The high-speed mode will also cause the weight to shift rearward, which will improve the grip of the rear wheels. The front-to-rear weight distribution of 50/50 should be the best ratio.

4WD: AWD also belongs to the 4WD range. , just means full-time 4WD. But daily 4WD usually refers to part-time 4WD.

The system can usually only be used in low-speed traction situations. The understanding of torque is also the key to understanding 4WD, as explained earlier. Wheel differential lock: For part-time 4WD, it is usually found on the front wheel head. When driving in 2-wheel drive, The front wheels have no driving force. When turning on 4WD, the transfer case is connected to the front drive shaft, and the wheel differential lock must be closed to turn into 4WD. Structure: The main features of 4WD are two differentials and a Transfer case. The differential is located between the front and rear wheels respectively to transmit torque. When turning, the wheels rotate according to the speed output by the differential. When turning, the four wheels travel at different wheel speeds. The differential allows exceptions for the wheels. The speed is different.

Working principle: Usually an open clutch can distribute the torque evenly to the four wheels, but if one of the two wheels leaves the ground or walks on a smooth surface, the torque will change. If it is 0, the corresponding other wheel will also become 0. If this happens, both wheels will lose traction. Needless to say the consequences, right? You can lock the rear differential, even if one wheel leaves the ground It can also continue to move forward. 4WD cars have a stable start and good off-road performance, but their excessive mass results in a weak sense of speed.

[Suspension]

We still need to clarify the concept first, the so-called suspension It is the general name for all force transmission devices between the frame or the load-bearing body and the axle (that is, the wheel). It includes three parts: elastic elements, shock absorbers and force transmission devices. It can be divided into three parts according to the structure. There are two basic types of independent suspension and non-independent suspension. Non-independent suspension is generally used in conjunction with the overall axle. The rear suspension of off-road vehicles generally uses non-independent suspension. The left and right theory of non-independent suspension is They are not independent of each other, that is to say, when the position of one wheel on one side changes due to some reasons, the wheel on the other side will also change accordingly, while independent suspension is the opposite, and is generally used in conjunction with disconnected axles. It is commonly used in cars. The wheels on both sides are independent of each other. Even if the position and movement mode of the wheel on one side change, the wheel on the other side will not change.

Understand the basic concepts, We are now beginning to understand its principles and functions. The most critical parts of suspension are springs and shock absorbers.

Spring

The function of the spring is the most direct and easiest to understand. Through It expands and contracts itself to slow down the vibration caused by the road surface. We all should know that in daily life, if we press the spring hard, the length of the spring after letting go will be longer than the original length, so the rebound of the spring cannot be controlled. If the car becomes bumpier, the shock absorber can solve this problem. The shock absorber is used to control the rebound of the spring. When the car drives over an uneven road, the spring rebound causes the car to bounce up, so that the tire It will leave the ground, causing the car itself to lose its grip. The shock absorber can keep the spring pressing the tire to the ground at this time to maintain smooth contact between the car and the road.

The car suspension is soft or Harder springs are mainly determined by the selected springs. Softer springs can undoubtedly improve driving comfort, absorb bumps on the ground, and maintain good grip, while harder springs can reduce body shaking and enhance Generally speaking, sports cars and sports cars will use hard springs to improve the handling performance of the car. Modifying the springs can improve the handling performance. The main modification is to use harder and shorter springs. The advantages of harder have been mentioned above, and the advantages of short are Lower the body, thereby lowering the center of gravity and improving the car's high-speed stability when cornering.

Shock absorbers

Shock absorbers and shock absorber tubes, pistons, damping oil, valves and other components Composition and working principle: When the force needs to be compressed or rebounded, the piston is used to move up and down to push the damping oil through the small hole of the valve, and the heat energy generated is used to offset the vibration of the shock absorber cylinder. Control the spring return The resistance to elasticity is called damping. If the shock absorber produces greater damping, the shock absorber will be harder. Sports cars generally need to absorb large body shakes. In order to obtain good controllability at the same time, they will Use hard shock absorbers with large damping.

4 Some basic knowledge about cars

The modification of shock absorbers is similar to that of springs. For better control performance, damping is generally used. Large shock absorbers. If you want to change the damping, just change the aperture of the damping oil through the small hole of the valve. It is not good for racing cars and ordinary civilian cars to use the only damping setting.

Using adjustable shock absorbers is the right choice. Adjustable shock absorbers adopt an integrated design of spring and shock absorber.

Height adjustable damping, adjustable

The height can lower the center of gravity and enhance high-speed stability. The damping can be adjusted, the compression force and rebound force can be adjusted, and the steering can be precise to enhance the controllability.

Adjustment, low-speed corners: not steering when entering the game can reduce the front shock absorption. The damping of the cylinder is increased at the same time, and the damping of the rear shock absorber is increased. Oversteer can be adjusted in the opposite direction. Understeer is given when exiting the corner. The rear shock absorber can be adjusted to be hard on the FF car, and the front shock absorber can be reduced on the FR car. Medium and high speed corners: understeer when entering the corner. The damping of the rear shock-absorbing tube can be increased, and the opposite is true for oversteer. The hardness of the rear shock-absorbing tube can be adjusted when the oil is supplied out of corners and understeer is applied. Height: low in the front and high in the rear tend to oversteer, while high in the front and low in the rear tend to understeer.

[Body]

It is the favorite of many people who like to modify, but a large number of people just like the visual impact brought by its appearance, but do not understand the true meaning and function of its existence and installation< /p>

Spoilers are some plates installed on the car body, used to improve and balance the power and stability of the car when driving at high speed. In aerodynamics, the flow rate of the air and the pressure of the air are It is inversely proportional, that is to say, the faster the air flow rate is, the smaller the pressure will be, and vice versa.

The side shape of the car will cause the air flow pressure to be larger and smaller at high speeds. , in this way, there will be an upper and lower pressure difference to generate lifting force. The faster the vehicle speed, the greater the pressure difference will be, that is, the lifting force will increase and become more and more obvious. It is part of the air resistance that the car experiences while driving. , the lifting force will not only consume the power of the car itself, but most importantly, it will reduce the adhesion between the wheels and the ground, which will make the car float and the stability when driving will also become worse, so now there are various The main purpose of the appearance of spoilers is to gain extra downforce for high-speed cars so that the tires can grip the ground better and drive more stably.

Tail wing

According to the above As mentioned, when the vehicle speed exceeds 60 km/h, the impact of air resistance on the vehicle is very obvious. The use of the car's rear wing can produce an additional force, namely downforce. That is, the adhesion to the ground. It can offset part of the lift force, control the car's floating, reduce the impact of wind resistance and keep the vehicle close to the road, thus improving stability. Installing a rear wing can also save fuel. Generally speaking, small displacement vehicles should not install a rear wing because of the speed of the car. It still cannot reach the speed at which the rear wing can play a positive role. Instead, it only increases the mass of the car body. It is still necessary to install a rear wing on large-displacement cars.

Nowadays, rear wings are basically made of three kinds of materials. One is made of fiberglass material equipped with the original car, which fits the curves of the car body better. The other is made of aluminum alloy material. The general appearance is exaggerated, but the diversion effect is indeed good, but the excessive mass is also a major disadvantage. Best The material can be said to be a carbon fiber tail wing, which has high rigidity and durability, and is small in weight and beautiful in appearance. The position of the spoiler on the tail wing is somewhat adjustable, and the adjustment methods are manual and automatic. The automatic adjustment is controlled by hydraulic pressure. , the angle can be automatically adjusted according to the vehicle speed, and manual adjustment is more convenient. The bigger the rear wing, the better, because the main function is to provide downforce to make the car more stable at high speed, so as long as it has the best spoiler effect, there is no need to add extra quality burden.