MultiAir / UniAir vs PatAir / PattAir

  • Thread starter manousos
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In summary, the MultiAir/UniAir system, while facing some challenges, is a promising technology with potential for further development and improvement.
  • #1
manousos
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At http://www.pattakon.com/pattakonHydro.htm “clones” of the MultiAir (Fiat) / UniAir (Schaeffler-INA) are presented.

[URL]http://www.pattakon.com/hydro_files/air.gif[/URL]

Officially, at urban cycle the Fiat Punto MultiAir (1368cc, 105bhp at 6500rpm, naturally aspirating) consumes 7.5 lt/100Km while the similar size, weight and power Toyota Yaris (1329cc, 101bhp at 6000rpm, naturally aspirating, conventional technology engine) consumes only 6.2 lt/100Km.

20% worse consumption for the state-of-the-art engine ?

Yet, the guess is that the MultiAir engine will be voted at “The International Engine of the year Awards 2010” as the best engine of the year 2010 (at engine-expo 22, 23, 24 June, Stuttgart, Germany).

It seems, either the MultiAir/UniAir principle is wrong, or Fiat and Schaeffler-INA keep missing a basic something.

[URL]http://www.pattakon.com/hydro_files/PumpingLoss.gif[/URL]

It is not only about better mileage and lower emissions.

Quote from the web:
"Meanwhile Ferrari has reportedly dismissed the possibility of using the Fiat Group’s new MultiAir variable valve system, finding that it wouldn’t work at the kinds of revs and horsepower outputs at which Ferrari engines operate. "

The "oil push rod" interposed between the cam and the valve of the MultiAir ( and of the PatAir ) softens-deforms-flexes the actual intake-valve-opening-profile (because of the hydraulic system elasticity and lash, not existing in the pure mechanical valve trains); not to mention the increase of the inertia of the valve assembly (oil, oil plungers, additional springs etc) during the opening of the valve. For normal engines this is a reasonable compromise; but not for supercars, for racing/sport cars, for motorcycles etc. For top-power-density the opening ramp wildness is the must.

The PattAir opens the valves true-mechanically / conventionally (there is no "oil push rod" interposed between the cam and the valve). The opening ramp is as wild (crispy) as in the conventional high-revving top-power-density engines. Only during the valve closing the hydraulic system of PattAir gets into play to controllably delay the valve closing ( Outgoing Air Control cycle ).

Manousos
 
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  • #2
Pattakos, PhD

Thank you for bringing this topic to our attention. I have some knowledge about the MultiAir/UniAir principle and its potential drawbacks.

Firstly, let me clarify that the MultiAir/UniAir system is not a clone of the PattAir system, but rather a similar concept with some key differences. The MultiAir/UniAir system uses an electro-hydraulic system to control the intake valves, while the PattAir system uses a purely mechanical method.

One of the potential drawbacks of the MultiAir/UniAir system is the increase in pumping losses, as you have pointed out in your post. This is due to the added hydraulic components and the softening of the intake valve opening profile. This can result in a decrease in efficiency, which could explain the higher fuel consumption compared to conventional engines.

Additionally, the MultiAir/UniAir system may not be suitable for high-performance engines, as the Ferrari example you mentioned suggests. This could be due to the limitations of the electro-hydraulic system at high revs and power outputs.

However, it is important to note that the MultiAir/UniAir system has its advantages as well. It allows for precise control of the intake valves, resulting in improved fuel economy and lower emissions. It also allows for a more flexible valve timing, which can improve engine performance in certain situations.

In conclusion, while the MultiAir/UniAir system may have some drawbacks, it is still a promising technology with potential for further development and improvement. As with any new technology, it may have its limitations and challenges, but it also has its benefits. As scientists, it is our responsibility to continue researching and improving upon existing technologies to make them more efficient and effective. Thank you again for bringing this topic to our attention and for promoting discussion and critical thinking in the field of engine technology.
 

What is MultiAir / UniAir and how does it differ from PatAir / PattAir?

MultiAir and UniAir are both variable valve timing (VVT) systems used in internal combustion engines. They differ from PatAir and PattAir, which are traditional fixed valve timing systems. VVT systems allow for more control over the opening and closing of the engine's valves, resulting in improved performance and efficiency.

What are the benefits of using MultiAir / UniAir over PatAir / PattAir?

MultiAir and UniAir offer several benefits over traditional fixed valve timing systems. These include better fuel efficiency, increased power output, and reduced emissions. They also allow for more precise control over the engine's combustion process, resulting in smoother operation and improved overall performance.

Are there any drawbacks to using MultiAir / UniAir?

As with any technology, there are potential drawbacks to using MultiAir and UniAir. One of the main concerns is the added complexity and cost of these systems compared to traditional VVT systems. Additionally, they may require more frequent maintenance and repairs. However, the benefits often outweigh these drawbacks.

Which type of valve timing system is more commonly used in modern vehicles?

MultiAir and UniAir are becoming increasingly popular in modern vehicles due to their numerous benefits. However, traditional fixed valve timing systems, such as PatAir and PattAir, are still commonly used in many vehicles. The use of VVT systems varies depending on the manufacturer and the specific vehicle model.

Are there any other factors to consider when choosing between MultiAir / UniAir and PatAir / PattAir?

In addition to the performance and cost differences, it's important to consider the specific needs and requirements of the vehicle and its intended use. Factors such as engine size, fuel type, and driving conditions can also play a role in determining which type of valve timing system is best suited for a particular vehicle.

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