Engine common sense
Simply speaking, an engine is an energy conversion mechanism. The thermal energy of gasoline (diesel) is used to burn gas in a sealed cylinder. When the gas expands, it pushes the piston to do work. Converting it into mechanical energy is the most basic principle of the engine. All structures of the engine serve energy conversion. Although the engine has accompanied the automobile for more than 100 years, it has greatly improved in terms of design, manufacturing, technology, performance and control. The basic principles remain unchanged. This is an era rich in creativity. Engine designers continue to integrate the latest technology with the engine, turning the engine into a complex mechatronics product, making the engine performance nearly perfect. extent.
Classification of engines
Modern high technology is perfectly reflected in engines, and some new technologies and new structures are widely used in engines. Such as V12, V8, and V6 engines: they all mean that the cylinders are arranged in a V shape. This kind of engine makes full use of dynamic principles, has good stability, increases engine displacement, and reduces engine height. For example: Audi A8 6.0 uses a W12-12 cylinder V-type engine, BENZS600 uses a V12-12 cylinder IV-type engine, etc.
Generally, engines are divided into 3-cylinder, 4-cylinder, 6-cylinder, and 8-cylinder types according to different displacement sizes. At present, most cars with a displacement of 1.3L-2.3L use in-line four-cylinder engines, which are characterized by small size, simple structure, and easy maintenance. Displacements above 2.5L generally use multi-cylinder designs, including in-line 6-cylinder engines, such as BMW; There are also V-shaped 6-cylinder engines arranged on both sides at a certain angle, which can effectively reduce vibration and noise, such as the Buick series; generally speaking, the larger the displacement, the higher the power of the engine. But now there are also some small-displacement cars that use technologies such as turbocharging, multi-valve, and variable timing to increase power.
Engine performance
Engine performance parameters are the parameters that best reflect the engine's working ability, mainly including: displacement, maximum power, and maximum torque.
Displacement is often associated with engine power. The size of displacement affects the level of engine power. It is usually used as a standard for classifying high-, medium-, and low-end cars. The piston moves back and forth up and down in the cylinder, so the reciprocating motion must have a highest point and a lowest point. The cylinder volume swept by the piston from the lowest point to the highest point is called the single-cylinder displacement, and the sum of the displacements of all cylinders is called the engine. Displacement. Maximum power and maximum torque are two concepts that are most easily confused. Some people think that the greater the power of the car, the greater the force, but this is not the case. The same 300 horsepower can drive the car to a speed of more than 250 kilometers/hour on a sports car, but on a container truck, it may only reach a speed of 150 kilometers/hour at most, but it can drag a 30-40-ton truck. container. The secret here is that the torque of the two cars is very different. Simply put, the power is expressed at high speeds. On the engine performance curve, it increases significantly as the speed increases. It determines how fast the car can run. , torque does not necessarily develop at high speeds, and is relatively flat on the curve. It can determine the power of the car when driving, including acceleration.
When interpreting the engine parameters, it is important to note that you should not only look at the power, but also the torque parameters, and pay attention to the speed when the engine is at maximum power and maximum torque. Of course, in terms of speed A slightly lower value is better.
Basic features of the V10 engine
1. The clutch housing is fixed to the engine with titanium alloy bolts.
2. The carbon fiber air tank that supplies air to the engine's air injection system is located above the driver's head.
3. In the engine valve system, each cylinder has 4 valves.
4. The engine’s fuel injector is machined from a single piece of metal.
5. The camshaft is now gear-driven, whereas the 1989 RS1 Renault V10's axle was belt-driven.
6 Valve springs are no longer used in the valve distribution system, and the valves are now controlled by compressed air.
7. In order to avoid using steel pipes as much as possible, oil and water circulation channels are cast into the cylinder wall. What materials are used inside the engine?
Aluminum is the most common material used in Formula One racing engines today. In the 1980s, cast iron had all been replaced by lighter aluminum. Aluminum also replaces magnesium, which corrodes when exposed to water.
Only moving parts that must withstand strong forces are made of steel. The basic distribution of materials is as follows:
Aluminum: 63% (cylinder head, oil pan, piston)
Steel: 29.5% (camshaft, crankwheel, timing gear)
Magnesium: 1.5% (oil pump housing)
Carbon fiber: 1% (air tank, coil cover)
Titanium: 5% (connecting rod, fasteners)
It takes more than 150 employees to manufacture an engine, including 28 engineers, 20 draftsmen, 35 engine mechanics, 8 electronics experts, 20 machinists and assemblers, and 4 system technicians Engineers, 6 bench experiment technicians, 15 people engaged in procurement, production and inspection, and another 15 people as management personnel. Turbocharged engines: Over the years, Formula 1 engines have become more compact, lighter and more fuel-efficient. At the same time, power increased, and turbocharging reached its peak from 1977 to 1988. The most advanced engines at the time, including BMW, Porsche, Renault, Ferrari and Honda, had verified power of more than 1,200 horsepower. This engine changed the face of Formula One racing. In 1977 no one believed that a 1.5-liter turbocharged engine could beat a 3-liter naturally aspirated engine. This is perhaps the best engine in Formula 1.
Explanation of terms
Let’s clarify several concepts related to the engine
>> Piston dead center and stroke:
a) The two extreme positions of the piston's reciprocating motion in the cylinder are called end points. The farthest position of the piston from the center of the crankshaft is called top dead center, and the position farthest from the center of the crankshaft is called bottom dead center.
b) The distance between the upper and lower dead centers is called the stroke of the piston. A half-turn of the crankshaft is equivalent to one stroke of the piston.
>> Displacement
a) The piston reciprocates in the cylinder, and the volume in the cylinder changes continuously. When the piston is at top dead center, the space formed by the top of the piston and the inner surface of the cylinder head is called the combustion chamber. This spatial volume is called the combustion chamber volume.
b) The volume of space through which the piston moves from top dead center to bottom dead center is called cylinder displacement. If the engine has several cylinders, the sum of the working volumes of all cylinders is called engine displacement.
c) When the piston is at the bottom dead center position, the entire cylinder volume above the piston top is called the total cylinder volume.
>> Compression ratio
a) The ratio of the total cylinder volume to the combustion chamber volume is called the compression ratio. The compression ratio represents the degree to which the gas is compressed in the cylinder when the piston moves from bottom dead center to top dead center.
b) The larger the compression ratio, the greater the degree of compression of the gas in the cylinder. The higher the pressure and temperature of the gas at the end of compression, and the greater the power. However, if the compression ratio is too high, knocking will easily occur.
c) Compression ratio is an important structural parameter of the engine. Due to different fuel properties, different types of engines have different requirements for compression ratios. Diesel engines require a larger compression ratio, generally between 12-29, while gasoline engines require a smaller compression ratio, between 6-11.
>> SOHC
Engine types classified according to the number of camshaft positions. SOHC stands for single overhead camshaft engine and is suitable for 2-valve engines.
>> DOHC
DOHC stands for double overhead camshaft engine, suitable for multi-valve engines. Usually, engines have 2 valves per cylinder, and in recent years, 4-valve and 5-valve engines have also appeared. This undoubtedly opens up a way to improve the intake efficiency and power of the engine at high speeds. This type of engine is suitable for high-speed engines and can appropriately reduce fuel consumption at high speeds.
>> Turbo
It is turbocharged, and its abbreviation is T. It is usually marked with 1.8T, 2.8T and other words on the rear of the car. Turbocharging has single turbocharging and twin turbocharging. What we usually refer to as turbocharging refers to exhaust gas turbocharging. Generally, the exhaust gas drives the impeller to drive the pump wheel, sending more air into the engine, thereby improving the engine speed. power while reducing engine fuel consumption.
>> VTEC
The Accord sedan engine produced in China uses VTEC technology. "VTEC" is the abbreviation of "Variable Valve Timing and Lift Electronic Control System" in Chinese. It is a "variable valve timing and lift electronic control system". VTEC is variable intake valve control technology, which changes the intake air volume and increases engine torque by changing the intake valve opening.
The entire VTEC system is controlled by the engine electronic control unit (ECU). The ECU receives the parameters of the engine sensors (including rotation speed, intake pressure, vehicle speed, water temperature, etc.) and processes them, outputs corresponding control signals, and passes The solenoid valve regulates the rocker piston hydraulic system, so that the engine is controlled by different cams at different speeds, affecting the opening and timing of the intake valve.
The VTEC engine has 4 valves per cylinder (2 inputs and 2 rows). The difference is the number and control methods of cams and rocker arms. It is the first in the world that can control valve opening and closing time and lift at the same time. Valve control systems for two different situations. The engine's combustion efficiency and performance can be greatly improved through computer-controlled valve timing and valve lift systems. Honda uses VTEC technology in almost all of its models, from the high-performance sports car S2000 to the hybrid vehicle INSIGHT, all using VTEC technology.
>> Electronic throttle technology
The electronic throttle eliminates the traditional throttle cable. Through the accelerator pedal sensor, the microcomputer controls the throttle, making the response more sensitive and the control more precise.
>> Multi-section variable intake manifold technology
The length of the intake pipe is controlled by computer to provide large torque at low speeds and high power at high speeds.
>> F.I.R.E
F.I.R.E means "integrated engine". It is produced in Italy, Brazil, Turkey and other countries, with an annual output of millions of units. It is a technology Mature and stable economical engines are widely used in Fiat's various economical cars.
Take the 188A4000 engine installed in the Fiat Palio sedan as an example. The engine displacement is 1242ml and the compression ratio is 9.5±0.21. The engine control system ECU is the Italian Marelli company's Magneti Marelli?IAW 59F multi-point electronic injection system. Using electrostatic ignition, sequential injection, non-return oil supply system and dual oxygen sensor technology, the engine emission level easily exceeds the European No. 2 standard and improves the safety of the entire vehicle. This system has the following functions: adjust injection time, control ignition advance angle, control radiator electronic fan, control and manage idle speed, control cold start compensation, self-diagnosis and self-learning, and has a limp function.
>> VVT-i
Most of the Toyota cars produced in recent years, including the latest Venza, are equipped with engines marked with "VVT-i". VVT-i is the abbreviation of "Variable Valve Timing intake" in English, which means "intelligent variable valve timing". Because it is controlled by an electronic control unit (ECU), Toyota has a nice Chinese name called "intelligent variable valve timing system". This system mainly controls the intake valve camshaft, and has a small tail "i", which is the code name of "Intake" in English. These are the literal meanings of "VVT-i".
VVT-i is a device that controls the intake camshaft valve timing. It optimizes the valve timing by adjusting the camshaft angle, thereby improving the engine's power and fuel efficiency in all speed ranges. Economical and reduce tail gas emissions. The new generation of Celica released by Toyota in 2000 further developed the VVT-i engine and created a new generation of VVTL-i engine. It also uses a principle similar to Honda's VTEC and has more camshafts than the original VVT-i engine. In addition to being able to switch cams with different angles, the "rocker arm" mechanism is also used to decide whether to push the high-angle or small-angle cam, so as to "continuously" change the engine timing, overlap time and "two "staged" progression.
VVTL-i combines VVT-i's continuously variable timing and overlap angle, and VTEC-style camshaft switching, and first achieves the first engine that can be said to be "nearly" perfect. VVT-i can be added to change the valve. The new engine VVTL-i after upgrading, indeed has the power of more than 100hp per liter in the performance version of Celica. The 1.8-liter version can have super power of 180hp/7800rpm, and it also retains a high and plain torque curve. performance, 0-96km/hr. It should be said that VVTL-i is Toyota's epoch-making masterpiece.
>> VDE
Variable Displacement Engine (VDE), and is ready to be installed on future cars and trucks produced by Ford to further improve the vehicle's fuel economy. This engine technology is most suitable for multi-cylinder engines. For example, for a 12-cylinder engine, after using this technology, it is equivalent to installing two independent 6-cylinder engines. One engine can be run according to driving needs, while the other is idle. In this way, the engine's exhaust volume can be adjusted at any time, thereby reducing fuel consumption.
BMW engines won five awards at the "International Engine of the Year Awards"
In the 2001 "International Engine of the Year Awards", BMW engines won 5 out of 12 awards, including Including the most important "overall winning award", BMW became the company with the most awards in this selection. In fact, BMW has been the most successful and strongest contender in this selection, known as the "Engine Oscars", since its launch.
The winning engines for BMW this year are:
○ The 3.2-liter, 6-cylinder engine equipped with the BMW M3 has a power of 252 kilowatts (343 horsepower) and a maximum torque of 365 Newton meters. There are three awards: "Best New Engine Award", "Best 3.0 to 4.0L Engine Award" and "2001 Overall Winner Award".
○ The 1.8-liter, 4-cylinder engine equipped in the BMW 316ti compact car is equipped with innovative "electronic valve" technology, 85 kilowatts (115 horsepower), and a maximum torque of 175 Newton meters. It won the "Most Powerful Engine" Best 1.4 to 1.8 liter engine award".
○ The 3.0-liter, 6-cylinder engine used in BMW 3 Series, 5 Series, X5 and Z3 cars, with a power of 175 kilowatts (231 horsepower) and a maximum torque of 300 Newton meters, won the "Best 2.5 to 3.0 liter engine award".