1. What is the VTEC called Honda Black Technology?
VTEC is variable? Valve? Timing? And then what? Valve? A compliment? Electronic? Control? The abbreviation of the system is variable valve timing and lift electronic control system. This technology was first developed by Honda in 1989. I-VTEC (Intelligent Variable Timing and Valve Lift Electronic Control System) is upgraded from VETC. Generally speaking, i-VTEC is to constantly adjust the valve opening time and size, so as to achieve the balance between maximum power and optimal fuel economy. The engine equipped with i-VTEC system can not only output more horsepower at high speed, but also ensure fuel economy at low speed.
In order to make the engine have high horsepower, it is a very simple and rude method to increase the valve size and let in more fresh air, but it will also increase fuel consumption. In 1990s, the valve timing and valve lift of the engine were limited by the design of camshaft profile, and the valve angle and opening time could not be changed. Can not meet the intake and exhaust requirements of the engine at different speeds. In order to give consideration to the high and low speed range, it is necessary to adopt a compromise camshaft profile design, which will seriously affect the performance potential of the engine.
I-? VTEC can automatically and continuously adjust valve timing and valve lift according to engine load. Different from the common engine cam with the same size, VTEC has three cam surfaces on the intake camshaft to support the three rocker arms on the rocker arm shaft respectively. When the engine is at low speed or low load, the three rocker arms are separated from each other, and the left and right rocker arms support the two intake valves respectively, so that the two valves have different timing and lift. When the vehicle speed increases, the sensor can control the hydraulic oil through the VTEC solenoid valve, so that the two intake rocker arms are connected into a whole. Just as the saying goes, "the sky falls, the tall man comes to the top", after the three cams are connected together, the largest cam will play a role and directly drive the valve, and the other two cams will lose their function. At this time, the valve opening angle is the largest and the time is the longest. With the increase of fuel injection, the engine power is greatly increased. Different working conditions get different power, which is the biggest advantage of VTEC.
2.2 What's the difference? DVVT and VTEC?
Like VTEC, DVVT is developed on the basis of VVT, which is twofold? Variable? Vale? The abbreviation of Timing literally translates into intake and exhaust double continuous variable valve timing mechanism. As can be seen from the name, DVVT can not only adjust the intake valve timing, but also continuously adjust the exhaust valve, but cannot control the valve lift. Because exhaust has a great influence on an engine, car owners who have modified the straight-through exhaust may know that the back pressure of the modified car is too small and the torque is too low, so the biggest advantage of adjusting the intake and exhaust valves at the same time is that it can achieve a large torque output at low speed, and a strong torque can be obtained by lightly stepping on the accelerator. DVVT engines usually burst into peak torque at 65,438+0,500 rpm, which is very helpful for low-speed driving in urban areas.
3. What are the disadvantages of the two engine technologies?
First of all, the VTEC engine is noisy at high speed. Of course, some people like the sound very much. Secondly, in the case of high-angle camshaft, the fuel consumption of the engine will increase significantly, which is about 30% higher than that of the engine with the same displacement under intense driving. Of course, this is also a disadvantage of strong motivation. Another point is that i-VTEC system needs the cooperation of complex ECU control unit, and the engine parts are complex, so the maintenance cost is naturally higher. At present, a large number of car companies, including some independent brands, are using DVVT. DVVT engine also has the problem of difficult maintenance. At the same time, the idle noise is high and the low torque is sufficient, but the high-speed torque is average.
Summary: Both technologies are aimed at improving engine efficiency, but VTEC is Honda's exclusive art, and DVVT is more common. Although it is not black technology, Honda applied for a patent for VTEC, which is more suitable for sports cars, so it has not been used by other brands.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.