Engine Technical Tour (13) Analysis of C4LEC8 Engine
【Pacific Auto Network Technology Channel】 1.6L was once the first choice for family cars because of its sufficient power and relatively low fuel consumption. However, with the improvement of consumption level, the size of family cars is getting bigger and bigger, and the power of 1.6L displacement is just enough. If the vehicle is fully loaded, it will be a bit of a small horse-drawn cart, and the driving pleasure has long been gone. 2.0L displacement power is sufficient, but high fuel consumption is inevitable. To make a compromise, 1.8L displacement power and fuel economy are the most suitable. I also saw this opportunity, and developed a brand-new 1.8L engine in five years. This engine code is EC8, which is currently mounted on Dongfeng models. This issue will bring you the technical analysis of Dongfeng EC8 1.8L CVVT engine.
Wonderful review of the last issue
● Basic engine parameters
● Research and development background of ●EC8 engine project
The research and development project of EC8 1.8L engine was put forward at the board of directors of Shenlong Company as early as April 2008, and was officially put into production in April 2013. The whole project development took five years.
In the two years before April, 2010, China market analysis and product technical scheme determination were mainly carried out. According to market analysis and laws and regulations, 1.8L will be the gold emission in the household market, and the power performance of 1.8L can best meet the household demand, while the fuel consumption and carbon dioxide emission also meet the environmental protection requirements.
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● Fuel consumption of ●1.6L and power of 2.0L displacement.
EC8 is a brand-new engine launched by PSA for China market. EC8 engine claims to have the fuel consumption of 1.6L displacement engine and the power of 2.0L displacement engine, and its performance level is in the advanced position of naturally aspirated engine.
It can be seen from the EC8 engine diagram that about 90% of the peak torque has erupted in the engine at 1500 rpm, and the torque curve is relatively gentle and lasts until 6000 rpm.
It has good dynamic performance in the daily use speed range, and reaches the peak torque at the earliest in the same class. The most intuitive feeling is that when the start accelerates, the low speed is very fast. The output that can be obtained in the 1500-2000 shift range that Chinese people are used to can be described as a little bit of power and a steady stream.
With the power of the 2.0L displacement engine, where does the fuel consumption of the 1.6L displacement engine come from? Of course, it depends on technology. For example, EC8 engine adopts cylinder honing technology, micro-grooved tile technology, variable displacement pump, DLC coated hydraulic tappet, intelligent timing gear damping technology, belt and so on. Listen to me together.
Before writing this article, Xiao Bian also visited the production workshop of EC8 engine. If you are interested, you can click the following link:
● Flat-top honing and micro-grooved tile technology
In terms of process flow, the cylinder block of EC8 engine is carried out in a small number of times by gradually adding power. In the last finishing process — — Flat-top honing
Flat-top honing can shorten the early running-in process and improve the fuel consumption and engine oil consumption during the running-in period. It can form a multi-reticulated small platform, which can greatly improve the lubrication condition of the friction pair, prolong the service life of the cylinder hole and piston ring friction pair and prolong the time. This technology is also widely called "pre-running-in" by experts, which can minimize the running-in wear of users when driving new cars, improve the reliability of vehicles to a greater extent, and save users’ maintenance costs.
In addition, crankshaft bearing has also adopted the micro-grooved tile technology. Micron grooves are machined on the surface of bearing bush by special machining method. The application of micro-grooved tile technology improves the compliance of bearing bush and accelerates the early running-in between bearing bush and crankshaft. Improve the fluidity of lubricating oil in the minimum oil film thickness area and enhance the cooling effect of engine bearing bush; The distribution area of lubricating oil film along the width direction of bearing bush is larger, which can increase the thickness of oil film in most high-pressure working areas and prevent the bearing bush from sticking.
The application benefits of micro-grooved tile technology are to reduce the mechanical loss of moving parts and improve the engine efficiency; Improve the reliability of moving parts and prolong the service life.
The combination of cylinder flat-top honing technology and crankshaft bearing micro-groove tile technology reduces the power consumption in crankshaft operation engineering. The inspection in the assembly workshop shows that the friction of crankshaft rotation needs to consume 3.6N·m engine torque.
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● Variable pump
There is also an oil pump directly connected with, and the operation of the oil pump also consumes a part. According to relevant foreign research reports, the use of variable displacement oil pump can generally reduce the fuel consumption of the engine by 1%-2%. To reduce the power consumption of the oil pump, it is necessary to match the oil supply of the oil pump with the actual oil demand of the engine. The use of variable displacement oil pump can meet this requirement.
The variable displacement oil pump used in EC8 engine is provided by Magna Powertrain (Changzhou) Co., Ltd.. EC8 oil pump is a variable displacement vane pump, which can be mainly divided into sliding variable vane pump and swinging variable vane pump. The variable principle of the two types of vane pumps is basically the same: the eccentricity between the outer adjusting ring and the rotor is changed by sliding or swinging, and then the displacement of the vane pump is changed.
When the feedback oil pressure reaches the variable set value, it is compressed, and the outer adjusting ring slides or swings, so that the eccentricity between the inner ring and the outer ring of the blade is reduced, and the variation of the oil pressure cavity formed between the blade and the inner and outer rings is also reduced correspondingly during the operation of the oil pump, thus reducing the oil pump flow; When the feedback oil pressure decreases, the spring gradually returns to reset the adjusting ring.
Main oil passage pressure feedback pressure control mode, which takes the feedback pressure point as the main evaluation point of engine pressure, has small pressure fluctuation and is close to the main lubricating parts, and can accurately reflect the engine oil pressure demand. By adopting main oil passage pressure feedback, the pressure control is more accurate and close to the engine demand, and the oil pump efficiency is higher.
The variable displacement pump keeps the pressure of the main oil passage of the engine at medium and high speed at a relatively constant value, which can meet the engine oil demand, reduce power consumption and play the role of energy saving and emission reduction. The variable displacement vane oil pump of EC8 engine is at the top level in China, with low power consumption and stable oil pressure control. Users can reduce engine power consumption and fuel consumption when driving a vehicle.
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●DLC coated hydraulic tappet
The working surface of EC8 hydraulic tappet is also coated with Diamond-like Carbon for short. The surface of DLC coating is black, which has comprehensive excellent properties such as stable quality, good adhesion with matrix, good wear resistance, low friction coefficient and good corrosion resistance.
The hardness of DLC coating can reach 8000HV, the friction coefficient is as low as 0.05~0.2, and the coating thickness is 0.5-10μ M, the highest heat resistance reaches 800℃.
After the tappet is coated, the surface friction coefficient is significantly reduced and the hardness is higher, which significantly improves the wear resistance of the tappet surface and greatly reduces the friction loss between the cam and the tappet surface. While reducing the working noise, it also reduces the power consumption of the engine, thus achieving the purpose of reducing fuel consumption and reducing the cost of car use.
● Intelligent timing gear damping technology
Through the special formal gear profile design, a controlled and periodic phase interference is formed to eliminate the torsional vibration of camshaft and reduce the dynamic tension of belt.
The processed crankshaft timing gear is approximately oval, which can significantly reduce the timing error of camshaft, effectively reduce the dynamic tension of belt, effectively reduce the dynamic and static axle load and improve the service life of belt.
It can be seen from the curve that the vibration of the intelligent timing system is reduced and the engine runs quieter. According to reports, the life of the intelligent timing system is equivalent to that of the engine. The belt tension is reduced and the bearing life is effectively improved. It reduces the noise and vibration of the user’s timing system when driving, and improves the driving comfort of the vehicle.
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EC8 piston adopts the latest technology of FM-Federal-Mogul Company: ELASTOVAL II structure and fully floating piston pin, which optimizes the piston design structure, removes the back mass of piston ring support area, reduces the piston weight and friction loss, and realizes the lightweight of the piston while maintaining sufficient strength of the piston. Elastoval II comprehensively considers the skirt, thickness, profile and other factors, combined with the cylinder clearance and pin hole eccentricity, in order to achieve the best energy-saving and noise-reducing effect, and is conducive to reducing fuel consumption and increasing its fuel.
EC8 improves the engine performance to a great extent by increasing the volume of the piston head projection to 11. The special piston structure design also improves the reliability of engine operation and reduces the cost of users’ cars.
●CVVT timing technology
CVVT is a technology that changes the opening time of camshaft by electro-hydraulic control system, so as to control the required valve overlap angle. This is not a novel automobile technology. Now many engines have adopted this mature and reliable technology.
EC8 engine adopts the VVT technology of INA, which can adjust the intake valve timing and phase in a wide range of angles to ensure that the engine can meet the requirements of middle and low speed and high speed at the same time. The driving comfort, fuel economy and emission are obviously improved. CVVT technology can ensure the charging efficiency of the engine under different working conditions and improve the low-speed end torque by 5-10%. 5-8% high-speed power is increased, so that users can get better power output when starting at low speed, and high engine power is maintained at medium and high speed. The fuel economy can be improved by 1-3%, making the vehicle more fuel efficient. Under the limited NOx level, HC emission can be reduced by 25% at most, and the stability at idle speed is improved, and the driving comfort is better.
Summary:Throughout the whole paper, EC8 engine should have many advanced engine technologies besides the original mature, stable and reliable technologies. The development time is relatively short, the cost is relatively low, and the existing market resources can also be used to some extent. The same is true from the user’s point of view. What users are most worried about is whether the performance is stable or not, and it is not easy to buy accessories when there is a fault, which just solves these problems. With five years’ unremitting efforts, the brand-new EC8 engine has been developed with "high efficiency, low consumption and high reliability" in consideration of power, fuel consumption, comfort and reliability. The slogan of the power of the 2.0L engine and the fuel consumption of the 1.6L displacement engine will never be groundless.
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