After so many years of engine development, someone finally thought of giving up the camshaft
The previous article is continued, and the book is continued (refer to June 30, 'For the engine to burn, engineers have smashed the intake valve for decades.' Last time, I talked about how to make the engine burn better, and the key parts One is the 'intake valve' that is responsible for air entering the cylinder. For the engine combustion, engineers have worked on the intake valve for decades...
From two valves per cylinder (one intake and one exhaust) to the current general four valves per cylinder (two intakes and two rows), the intake valves change from variable timing VVT and variable lift. Most of them There are two characteristics that cannot be changed. The first is that the valve opening is not linear and can only be achieved in one or more stages; the second is that they are inseparable from the mechanical mechanism of the camshaft.
With the development of electronic technology, one day the Italians suddenly came up with a ghost idea-why not give the opening of the intake valve to the hydraulic and solenoid valves to control, and all the camshafts The class is removed, and it is completely electronically controlled. The cost can be reduced without a camshaft, and the structure is simple and reliable.
This technology is Fiat’s Multiair, which was later widely used in the same door. On the Jeep model.
In order to show you the internal structure of the Multiair engine most intuitively, we took a trip to GAC Fick’s Guangzhou factory and used one in Jeep. The 1.4T Multiair engine above the guide is disassembled, and this structure is presented for the first time...
The working principle of Multiair
At the 2009 Geneva Motor Show, Fiat officially Released the Multiair electronically controlled hydraulic air intake system technology. Since 2010, engines equipped with Multiair technology have won the 'International Engine Award' for several consecutive years. The second-generation Multiair 2 system is now used on the Jeep model, which is more than the first The first generation is more intelligent.
Ordinary engines have two camshafts responsible for opening four valves per cylinder (even BMW Valvetronic has two), while Multiair has only one. Among them, the exhaust valve The camshaft is directly connected mechanically, which is no different from ordinary cars.
The difference lies in the end of the intake valve. Connecting the intake valve is a hydraulic chamber. The amount of oil in this hydraulic chamber can be passed through. Into the solenoid valve for precise control, this is the essence of MultiAir's omnipotence.
Then the intake valve, hydraulic pressure The cavity system will still be connected to the camshaft through a small piston. If the hydraulic cavity and solenoid valve do nothing, the intake valve is equivalent to being directly driven by the camshaft, which is the same as a normal engine.
But the key is that the solenoid valve and hydraulic chamber are here to do things. Under its control, the valve can be opened in various ways at will, including the opening angle and time can be controlled, thus What are the effects achieved by various technologies such as VVT, VTEC, Valvetronic, etc.?
◤After removing the cylinder head, the silver box on the left is the Multiair system, and the right is the camshaft on the exhaust side. ◤ Disassembling the Multiair requires special tools to prevent damage to the precision system. For example, MultiAir has a trick called 'Mulilift multiple lift.
The advantages and disadvantages of Multiair
Any new technology has its advantages and disadvantages, depending on whether the advantages outweigh the disadvantages, then it has application value.
◤This is the disassembled Multiair module, packaged into a whole1. The electronic equipment of Multiair responds very quickly, even faster than the mechanical structure directly driven by the camshaft, just like Mulilift multiple lift Only electrons can do this kind of reaction speed.
2. It can realize the 'stepless adjustment' of the air intake, including time and On the lift. Last time it was mentioned that BMW Valvetronic can achieve linear control, but its complex structure can only be used in expensive luxury cars, while the Multiair structure is much simpler.
3. Since the intake air volume can be controlled at will, there is no need for extra throttle (intake air The mechanism before the door), which makes the structure of the intake duct simpler, the air intake is smoother and the engine works more efficiently.
4. The structure is very sophisticated and requires professional maintenance. The production of the Multiair system is provided by Schaeffler, Germany. The key solenoid valve technology is developed by Fiat and Continental. The precision is very high and the problem of wear and tear after long-term use must be solved.
5. At present, the Multiair engine on the Jeep model does not have direct injection in the cylinder! In-cylinder direct injection is an important technology to improve engine power and efficiency. Although Multiair performs well, it does not mean that it can technically leave the Volkswagen EA211 1.4TSI engine.
But from the actual test drive experience, I still prefer Mulitair, its high-turning sound line is more charming, and the power is more linear and controllable. On the other hand, without direct injection technology, Mulitair engines have low oil requirements. Jeep even claimed that this 1.4T engine uses No. 89 fuel in the test, and there is no problem in short-term use.
Finally, I still want to emphasize that having a good engine is only an important step in becoming a good car. Compared with the excellent performance of the engine, the performance of the Jeep Guide's 7-speed dual-clutch gearbox can not keep up with the rhythm, becoming a short board that restricts the Guide's 1.4T power output.
The use and installation of performance camshaft is compared with most other systems for managing the steel camshaft effectively and no doubt performance camshaft have won the race so many times.
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