The new Honda Fit is about to be launched in China, but this time Honda did not take the risk of directly using the 1.0T three-cylinder engine that is standard on foreign Fits as the power of the new Fit. Instead, it chose to retain the original well-received engine. Honda 1.5L self-priming engine.
Judging from the current acceptance of three-cylinder engines by domestic users, Honda’s choice for the new Fit this time is undoubtedly quite safe.
However, among Japanese brands, Honda was the first to try to promote turbocharged direct-injection three-cylinder engines.
The 1.0T three-cylinder engine currently promoted by Honda in China? With Honda’s strong brand power and Lingpai’s accurate model positioning, Lingpai seems not to be hindered by the three-cylinder engine strategy like GM and Ford. Sales volume continues to remain above 10,000 units per month, making it the best-selling three-cylinder car in China.
Today let’s take a look at the strength of Honda’s successful 1.0T three-cylinder engine.
▍Technical Background
Honda’s engines used to be god-like in the naturally aspirated era. They were strong and stable, with very low fuel consumption. In China, there were even Hondas that “buy engines and give them to cars” "The statement shows Honda's accomplishments in naturally aspirated engines.
With the popularization of supercharged direct injection technology, its advantages of high performance and low fuel consumption have become more and more obvious. Honda also began to study supercharged direct injection gasoline engines after 2010, and around 2015, it Launched three series of supercharged direct injection gasoline engines: 2.0T, 1.5T and 1.0T.
Honda’s supercharged direct-injection gasoline engine inherits its famous VTEC technology in the naturally aspirated era, which is variable valve lift technology. Honda calls its turbocharged direct-injection engine VTEC? TURBO series, which is VTEC supercharged engine.
According to Honda's product planning, the VTEC-TURBO series supercharged direct injection engine series will be used to replace the previous VTEC naturally aspirated engine series from 1.5L to 3.5L to achieve engine miniaturization.
Of course, Honda still retains the naturally aspirated engine technology in hybrid power, and considering the actual situation in the country, the 1.0T three-cylinder engine has also completely replaced the original well-received 1.5L naturally aspirated engine. Four-cylinder engine.
▍Honda’s 1.0T three-cylinder engine technical solution
The first point is its technical source.
The basic structure of Honda's 1.0T three-cylinder direct injection supercharged engine is still derived from Honda's highly praised 1.5L naturally aspirated direct injection engine.
This can be seen clearly from the comparison of the core structural parameters of the engine. The bore, cylinder center distance and valve angle of the two engines are exactly the same, and because the latest 1.5L naturally The aspirated engine is also direct-injected, so the positions of the direct-injection injectors are exactly the same.
Of course, this 1.0T three-cylinder engine does not simply reduce one cylinder, but has redeveloped almost all systems. Although it has a deep connection with the original 1.5L four-cylinder engine, it is technically It looks like it should be a brand new engine.
The second point is the design of the direct injection injector and combustion system.
The 1.0T direct injection injector adopts a 6-hole design. The flow distribution adopts a design of four large holes in the middle and two small holes on the sides. It cooperates with the newly designed piston top to reduce the direct impact of the injection oil beam. The wet wall effect on the piston and cylinder bore reduces oil dilution and is also beneficial to particulate matter emissions.
Honda has redesigned a new air passage for the 1.0T based on the structure of the 1.5NA self-priming engine to adapt to the needs of the supercharged engine and the Atkinson cycle. The main goal of air passage design is to increase the intensity of tumble flow and further increase the combustion speed, thereby improving the engine thermal efficiency level.
The figure below shows the difference in airway design between the 1.0T three-cylinder engine and the 1.5L naturally aspirated engine.
The third point is VETC and Atkinson cycle technology.
VETC is Honda’s specialty technology. It was very successful in the naturally aspirated era and became a golden signature of Honda engines.
Honda VTEC is actually a two-stage intake variable lift system, which realizes valve lift switching through the variable mechanism on the valve rocker arm.
This 1.0T VTEC system is installed on the intake side. At the same time, Honda also equipped this 1.0T engine with intake and exhaust dual VVT, which is a variable valve timing system. Honda calls it for VTC.
The combination of VTEC and VTC can further optimize the different requirements of high performance and low fuel consumption on camshaft timing lift.
Honda uses this system with variable valve lift and timing on the 1.0T to realize the Atkinson cycle at low load through the low-lift intake valve early closing scheme, which is the actual expansion ratio. When the compression ratio is large, the main goal is to reduce fuel consumption.
Honda’s test results show that the VTEC technology on the 1.0T can reduce the vehicle’s cycle fuel consumption2.
As can be seen in the figure below, compared to the previous 1.8L naturally aspirated engine, Honda's 1.0T has greatly increased the torque and significantly reduced the fuel consumption rate, with the maximum thermal efficiency reaching 36.1. Moreover, the distribution of low fuel consumption zones is wider, which is very helpful for reducing fuel consumption under actual driving conditions of the vehicle.
The fourth point is the integrated exhaust pipe and single-scroll supercharger.
The 1.0T engine adopts a cylinder head integrated exhaust pipe design. This design has two significant advantages: First, it can quickly heat the engine cooling water with the exhaust temperature, which can quickly warm the engine. machine, reducing fuel consumption and emissions.
At the same time, under large loads, the water jacket outside the integrated exhaust pipe can use the cooling water of the cylinder head to reduce the temperature of the exhaust, protect the supercharger, and avoid unnecessary enrichment of exhaust temperature protection.
The cylinder head and integrated exhaust pipe of Honda's 1.0T engine adopt a relatively advanced upper and lower stratified cooling method, which allows the colder water to cool the lower part of the cylinder head water jacket first. Provide sufficient cooling capacity to the combustion chamber to prevent thermal deformation of the cylinder head.
This 1.0T engine uses a single scroll supercharger. And an electronically controlled bypass valve is used to improve the response speed of the turbine and improve fuel consumption under partial load of the engine.
The fifth point is the continuously variable oil pump.
Honda 1.0T adopts a continuously variable displacement oil pump based on MAP control, which can adjust the displacement and output pressure of the oil pump according to the engine's needs for lubrication and oil pressure. Use lower oil pressure at low loads to reduce friction and reduce fuel consumption, and use high oil pressure at high loads to ensure lubrication needs.
Honda’s test results show that the potential of the variable oil pump to reduce fuel consumption is around 1 in the NEDC cycle.
The sixth point is the wet oil-immersed formal belt.
One of the biggest changes in the Honda 1.0T compared to the 1.5L four-cylinder naturally aspirated engine is to change the timing chain of the 1.5L engine to a wet formal belt.
Unlike the general dry formal belt, this wet belt requires engine oil lubrication. This timing belt combines the advantages of the traditional chain drive system and the dry belt, and has low noise. Low friction and maintenance-free.
Theoretically, the wet belt can have the same lifespan as the engine. At the same time, due to its small friction, it can reduce fuel consumption. Honda research results show that the oil-immersed timing belt can reduce the vehicle's fuel consumption by 0.6.
This wet belt was first used on Ford's 1.0T three-cylinder engine. Later, Honda 1.0T three-cylinder and Peugeot 1.2T three-cylinder also adopted this wet timing belt design. .
The most famous thing about the wet belt is the recall of Peugeot 1.2T. Peugeot 1.2T had a serious batch problem in which the timing belt fell out and blocked the oil circuit, causing engine failure. As a result, in early 2020 A recall was launched (see image below).
However, the Ford 1.0T and Honda 1.0T, which also use this technology, did not find this problem.
▍NVH noise and vibration level
Honda did not design a balance shaft for the 1.0T three-cylinder engine, so the vibration suppression of the three-cylinder engine is not ideal.
Honda has equipped the 1.0T three-cylinder engine with a start-stop system as standard on the Lingpai model. The engine will stop when idling, which can make up for the most troublesome idle vibration problem of the three-cylinder engine to a certain extent. .
In addition, in terms of noise, the control level of Honda 1.0T is not excellent, especially the noise level at low speed and full load is not ideal, and it is only average among the same type of supercharged direct injection engines. level. Compared with its own 1.8L naturally aspirated engine, the noise level is also worse to a certain extent (see the picture below).
▍Summary
Honda’s 1.0T adheres to Honda’s consistent style, has outstanding performance, and the power increase is almost the highest level in the industry.
The addition of VTEC technology and Atkinson cycle makes this 1.0 engine very competitive in terms of efficiency and fuel consumption, with a maximum thermal efficiency of 36.1, which is already high for a 1.0T small-displacement engine. Very good level.
Due to cost constraints, Honda 1.0T does not have a balance shaft, and its NVH performance is average.
This article comes from the author of Autohome Chejiahao and does not represent the views and positions of Autohome.