Hello everyone, I am Sir Li, Li Xie diesel engine, for you to interpret all aspects of diesel engine.
When introducing the Great Wall 4d20 diesel engine in the last issue, it was mentioned that there is also a light diesel engine with a double supercharging configuration in China, called SAIC π. A number of friends left a message for me to introduce, today Sir Li came to hand in his homework.
Although the Great Wall 4d20 is an excellent engine, as a veteran who has been tested in the market for 11 years, it has been slightly inferior in strength compared to some new fighters who have performed well. SAIC π is the most outstanding of these new fighters.
SAIC π double supercharged diesel engine
Obviously, SAIC π belongs to SAIC, but SAIC has many subsidiaries, and the development of π mainly involves the following two subsidiaries.
SAIC Maxus Automobile Co., Ltd., the youngest wholly-owned subsidiary of SAIC Motor, was established on March 21, 2011. The company mainly produces light passenger vehicles, mainly including "SAIC Maxus Maxus" brand MPV, SUVs, pickup trucks, wide-body light passengers and motorhomes. Saic Π was originally developed with the goal of upgrading the power of all maxus brand products to replace R425 and R428.
SAIC Maxus model diagram
Maxus was originally a brand of LLV, a British light commercial vehicle manufacturer formed by British truck manufacturer Leyland and Dutch daf, taking the three-word initial letters of Leyland daf vans to form LLV. Founded in 1993 to produce vans, light trucks and minibuses, the company struggled during the 2008 economic crisis and was formally acquired by SAIC in 2009. Because of its original foreign pedigree, maxus is more easily accepted by foreign customers, which is also a consistent method for many domestic companies to seize overseas markets.
SAIC Maxus v90 van car
Shanghai Diesel Engine Co., Ltd., formerly known as Shanghai Diesel Engine Factory, was founded in 1947. Mainly produces diesel engines and natural gas engines, and the product power covers 50kw to 1800kw, and has a variety of uses. There is an m series in its automotive engine products, and the displacement is also 2l, which is actually saic π. This also means that SAIC π is not exclusive to SAIC Maxus, but can also be adapted to other car companies with demand, after all, such an engine has a huge investment in research and development and equipment, and only by expanding sales can we quickly dilute the cost.
On the chai power
After 39 months of long-term development, the "SAIC π" engine was released on March 31, 2019, π is an infinite non-circulating decimal, implying infinite possibilities. SAIC π as the leader of domestic diesel engines in recent years, its technological advancement is obvious, in the 2020 "China Heart Top Ten Engines" selection, SAIC π became the only diesel engine among the award-winning engines.
SAIC π won the award
The advanced technologies used by SAIC π are as follows:
——21mpa burst pressure: the burst pressure refers to the pressure generated when the gas in the cylinder is burned, usually the higher the burst pressure, the lower the fuel consumption of the engine, and the greater the power at the rated point. To avoid high-pressure damage to the engine, it is often necessary to make the engine stronger, which leads to an increase in engine weight; or the use of better materials and processes, resulting in higher costs.
——Fuel injection pressure of 2000 bar: the higher the injection pressure, the better the fuel atomization effect, and the low fuel consumption when burning. The supplier is Wuxi Bosch, and among its domestic light diesel fuel system products, this is the one with the highest rail pressure.
2000 bar Bosch fuel system
----------------- Independent cooling of the cylinder head: the higher the engine temperature, the lower the oil viscosity, the lower the friction loss, and thus reduce fuel consumption, so the engine should be maintained at a higher temperature. Unlike the general engine only has a thermostat, the π body, cylinder head each has a thermostat, the engine in the cold start process, coolant only flows through the cylinder head, and does not cool the cylinder block, so as to achieve rapid warming.
SAIC π engine
——Water-cooled intercooler: Due to thermal expansion and contraction, under the same displacement, the lower the intake temperature, the greater the gas mass entering the cylinder, the more oil can be burned, and the higher the engine power. In addition, the lower the gas temperature, the lower the engine emissions. Intercooler is actually a radiator, there are two forms of air cooling and water cooling, the radiator is more than 100 degrees of air after the pressurization, the air cooler outside is the air blown in by the front grille of the car, and the water cooler is water outside the radiator. Obviously, water has a better cooling effect than air, but due to technical complexity and high cost, few diesel engines are adopted in China.
Water-cooled intercooler
——High and low voltage EGR: On the basis of the commonly used high voltage EGR system, an additional low-voltage EGR system is added. The low-pressure egr takes the exhaust gas from the post-treatment dpf and cools it back to the supercharger. Compared to high-pressure EGRs, low-pressure EGRs consume less fuel.
High and low pressure egr
Variable section supercharger (vgt version): The supercharger performance can be intelligently adjusted by electronically controlled actuator according to the engine operating conditions, that is, the load and speed of the vehicle.
Two-stage supercharger (dual supercharged version): The high-pressure stage uses a smaller variable-section turbocharger (vgt), the low-pressure stage uses a larger ordinary vent valve turbocharger (wgt), and the supercharger switching is controlled by three vacuum valves, which can take into account the low-speed transient response and the high-speed large intake. Compared to the vgt supercharger, the torque at a low speed of 1000rpm is increased by 20% using a dual supercharger and a maximum torque increase of 28%.
SAIC π double booster
——Two-stage variable oil pump: low pressure mode is used at low speed and small load conditions, and the power consumption of the oil pump is low; high pressure mode is used at high speed and high load conditions to ensure sufficient oil supply pressure.
- Variable eddy current: with a variable eddy current control valve, the engine needs less air when running at low speed, at this time close the control valve to make the eddy current ratio become larger, fuel and air are fully mixed; more air is needed when running at high speed, and the control valve is opened at this time to make the eddy current ratio smaller, so that the flow coefficient becomes larger.
Variable eddy current intake system
----------------- Close coupling doc+sdpf+scr post-treatment: on the one hand, doc and sdpf are installed close to the engine, the pipeline is short and the temperature is high, and the efficiency of after-treatment purification exhaust gas is high; on the other hand, SDPF is used, so that DPF also has the function of scr, which improves the purification efficiency of nox exhaust gas.
Partial satisfaction with China VIb emission regulations: Although the publicity is to meet The China VIb emission regulations, it actually satisfies only a small part of China VIb (only requires type I test to pass, ). At present, there are no diesel engines on the market that fully meet the requirements of China VIb, and the emission level of SAIC π is already in the first echelon of domestic products, and can be sold in cities that implement China VIb emissions in advance (such as Shenzhen, Guangzhou, etc.). The following are the specific requirements for emissions in Shenzhen, which was the first to implement China VIb.
Shenzhen's requirements for China VIb
SAIC π measures to reduce engine vibration and improve noise levels are as follows:
Noise reduction measures π by SAIC Motor
——Intake manifold silencer: Eliminates noise generated by the intake air flow.
-- Asymmetrically arranged balance shaft: integrated into the cylinder block, the asymmetrical arrangement can balance the overturning torque of the engine; with the use of a silent gear with coating, effectively improve the half-order noise of the engine.
——Generator OAD unidirectional pulley: reduce the speed fluctuation of the wheel train and improve the vibration and noise
——Sound insulation cover: the top is equipped with a composite sound insulation cover; the oil rail and injector are equipped with a flame retardant foam polyurethane sound insulation cover.
——Sandwich oil pan: sandwich sound insulation material in the middle, which can effectively reduce the noise at the bottom of the engine.
——Fuel pre-injection: During the engine's work at one time, the fuel is injected in multiple times, and a small amount of fuel is pre-injected before the main injection, which can reduce the pressure rise speed in the cylinder and reduce the noise.
--Crankshaft bias: By staggering the crankshaft centerline and the cylinder bore centerline to reduce the friction work of the piston at low and medium speeds, fuel consumption can be improved by 0.4% to 1.0%, and the nvh performance of the whole machine can be effectively improved.
Crankshaft bias technology
In order not to affect the reading experience, the technical introduction in the "Li Xie diesel engine" is a shallow taste, and then Li Sir will also do a separate "Li Xie Technology" series to expand the related technologies in detail, and interested friends can pay attention to the collection in advance.
The main parameters of SAIC π engine are shown in the following table, and the data comes from the official website of Shanghai Diesel Power.
Key parameters of SAIC π
The external characteristic curve of SAIC π engine is shown in the following figure.
External characteristics of SAIC π
At the beginning of the release in 2019, SAIC π sales of more than 8,500 units, and then gradually increased, in the first half of 2021 sales have exceeded 40,000 units, and the cumulative sales have exceeded 80,000 units. On the one hand, this climbing speed comes from the rapid switching of the power system of SAIC Maxus's entire series of products, and on the other hand, it also proves the strong competitiveness of SAIC Maxus models.
SAIC Maxus t70 pickup truck
But whether it is SAIC π or SAIC Maxus's SUVs and pickups, they all face strong opponents such as Great Wall Motors. If only from the perspective of diesel engines, SAIC π is undoubtedly more advanced in technology, but it also brings higher cost pressure. Although the engine is the core of the whole vehicle, but not all, SAIC Maxus as an emerging brand has developed rapidly, but from the sales side of the data, there is still a long way to go.
SAIC Maxus d90
Do you think SAIC Maxus will challenge Great Wall Motors' position in the future? Welcome to leave a message to discuss.
If this issue is helpful to you, please pay attention to and like it. I'm Sir Lee, a friend who accompanies you in your in-depth understanding of the engine.
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Diesel engine noise reduction, there are mainly these methods
【1】 SAIC Maxus official website, https://www.saicmaxus.com/strength.shtml
【2】 Shangchai Power official website, https://www.sdec.com.cn/about/1.html
[3] ldv, 360 Encyclopedia.
[4] SAIC Motor's engine, even yachts, power station enterprises are eye-catching, Shanghai Auto News
【5】 About the performance of the "SAIC π" engine, automobiles and new power