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Toyota Announces New Intake Valve Lift and Timing System

Valvematic
The Valvematic system. Click to enlarge.

Toyota Motor has announced its new variable valve lift mechanism, which it calls Valvematic. Valvematic combines the existing VVT-i (Variable Valve Timing-intelligent), which continuously controls intake valve opening/closing timing, with a new mechanism that continuously controls the intake valve lift volume.

In the case of a new 2.0-liter engine developed by Toyota, Valvematic improves fuel efficiency by 5% to 10% (depending on driving conditions), reduces CO2 emissions, boosts output by at least 10% and enhances acceleration responsiveness, according to the company.

TMC plans to introduce Valvematic shortly, starting with a new vehicle model featuring a 2.0-liter engine.

Valvematic adjusts the volume of air taken in by continuously controlling the intake valve lift volume as well as the timing of valve opening and closing. This boots performance based on the engine’s operational condition, helping vehicles achieve better fuel efficiency and dynamic performance.

Conceptually, this is similar to BMW’s Valvetronic, which also provides infinitely variable valve lift and timing, and delivers an approximate 10% reduction in fuel consumption. To implement Valvetronic, BMW uses an additional eccentric shaft, an electric motor and several intermediate rocker arms.

In 2006, Honda outlined its next-generation approach to valve lift and timing: Advanced VTEC (Variable Valve Timing and Lift Electronic Control System). A-VTEC also combines continuously variable valve lift and timing control with the continuously variable phase control of VTC (Variable Timing Control) to achieve a 13% improvement in fuel efficiency, compared to a production 2.4-liter i-VTEC engine. (Earlier post.)

Nissan also recently introduced its new Variable Valve Event and Lift (VVEL) and continuous valve timing control (C-VTC) technologies, which will be first applied on the Infiniti G37 coupe.

Nissan had earlier announced plans to install the VVEL system, which contributes up to a 10% reduction in fuel consumption and carbon-dioxide emissions compared to an engine of the same displacement without VVEL, on its products worldwide starting from FY07 under the Nissan Green Program 2010.

In the VVEL system, a rocker arm and two types of links close the intake valves by transferring the rotational movement of a drive shaft with an eccentric cam to the output cam. The movement of the output cam can be varied by rotating the control shaft within the DC motor and changing the fulcrums of the links. This makes a continuous adjustment of the valve lift amount possible. (Earlier post.)

Comments

Angelo

"....funding the multibillion-dollar PNGV (80mpg family sedan)- which amounted to nothing more than corporate welfare for GM Ford and Chrysler"

Actually, that effort produced some really good prototypes. It was the Bush administration which killed that program.

One such prototype that came out of that, the Dodge Intrepid ESX-3, which was the third and last generation of that concept. It was a mild-hybrid diesel with a lithium ion battery that achieved 72mpg. That came very close to the program's goal of an 80mpg family car.

They claimed they could produce that for $7500 more than a comparable gasoline powered car. I guess someone felt the public wouldn't accept that, but in hindsight, I wonder if that would have been the case if this program's funding continued.

I find it amusing - in my opinion, this ESX-3 was a more attractive vehicle than any that is presently in Dodge's lineup!

Angelo

Roger,
After reading your message regarding gasification, I noticed a piece that may interest you:

http://www.autobloggreen.com/2007/06/14/energyquest-to-invest-on-butanol-and-hydrogen/

It certainly sounds promising. Butanol does seem like a more efficient energy carrier for the fleet of vehicles already on our roads.

Raymond

Why do I think the 2.0-liter I-4 Valvematic engine could be the engine that will power the 2009 Toyota Corolla for the North American market?

Angelo

While I know it won't happen, it would be a great engine for the Camry hybrid. While the valvematic implementation itself apparently wouldn't provide significant benefit with hybrids (based on assumptions), the fact that an engine with roughly 17% less displacement could likely produce just as much torque surely would.

Al

I have a 2005 Pontiac Vibe. Is it normal to to have a 20-25% loss in fuel economy by driving at higher speeds than 110 km/hr. It seems if I keep it at 110 km/hr or lower the gas mileage is great but anymore than that it plumets. I do mostly highway driving. GM won't give me a straight answer and all I can put it to is the variable valve timing.

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