Automotive

Radical 4-in-1 piston engine promises hybrid-like efficiency

Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
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Unlike a 4-cylinder internal combustion engine (top) the opposing pistons in the Namikoshi engine are fixed onto a central hub unit that uses ball bearings
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Unlike a 4-cylinder internal combustion engine (top) the opposing pistons in the Namikoshi engine are fixed onto a central hub unit that uses ball bearings
The pistons in the concept engine move back and forth in a straight line thanks to a unique planetary, radial gear system
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The pistons in the concept engine move back and forth in a straight line thanks to a unique planetary, radial gear system
Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
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Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
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Initially designed for as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector
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One of the many challenges facing engine designers is the need to increase power output while simultaneously retaining or improving efficiency. Although a four-cylinder engine is still an engineering marvel, there remain many friction points that reduce energy output. Namikoshi Electronics of Japan believes its unorthodox 4-in-1 concept engine could provide an alternative powerplant to the automobile industry.

Over the past few years we’ve seen alternative combustion engines in various forms, from Duke Engines radical radial design to Volvo's450 hp triple-turbocharged four-banger. Now Namikoshi's low-friction engine is getting its turn in the limelight.

Initially designed as an electrical generator, Namikoshi realized that its 4-in-1 engine could possibly be adapted for use in the automotive sector. While it's laid out in a similar way to an opposing 4-cylinder found in any old VW or Porsche, Namikoshi Electronics’ 4-in-1 engine departs from convention by virtue of a big central unit surrounded by ball bearings, a central rod and a planetary gear.

Namikoshi claims that the design has significant advantages over traditional engines in terms of friction and vibration. Whereas four-stroke engines use lubricated friction bearings in the crankshaft, connecting rods and piston pins, Namikoshi’s engine has mounted opposing pistons onto a reciprocating hub that use ball bearings, thereby reducing friction.

Unlike a 4-cylinder internal combustion engine (top) the opposing pistons in the Namikoshi engine are fixed onto a central hub unit that uses ball bearings
Unlike a 4-cylinder internal combustion engine (top) the opposing pistons in the Namikoshi engine are fixed onto a central hub unit that uses ball bearings

And unlike the traditional engine where pistons are connected in-line to the crankshaft, Namikoshi has fixed the opposing pistons onto one central unit. The result enables the 4-in-1 engine’s connecting rods too move back and forth in parallel. Namikoshi claims this approach reduces vibration and the number of friction points when compared to a typical 4-cylinder engine, producing vibration levels similar to that of a rotary engine.

In the video below, you’ll see that instead of the pistons moving back and forth individually, they work in tandem. Namikoshi says this fixed design allows the engine to more efficiently "feed" off the opposing piston’s forces and removes energy-wasting mechanical linkages from the equation.

The pistons in the concept engine move back and forth in a straight line thanks to a unique planetary, radial gear system
The pistons in the concept engine move back and forth in a straight line thanks to a unique planetary, radial gear system

The Namikoshi concept engine weighs in at roughly 90 kg (198 lb), has a cubic capacity of 1,500 cc and measures approximately 800 mm (31.5 in) wide by 500 mm (19.7 in) deep and 250 mm (9.8 in) tall. Bore diameter is shown as 62 mm (2.4 in), while stroke for each piston is set at 125 mm (4.9 in).

If the 4-in-1 concept engine were to make it to market, Namikoshi believes it could significantly help to reduce emissions as outputs would be on par with that of a hybrid engine. However at this stage the company has not provided output specs or friction efficiencies relative to a traditional four-cylinder to back up the claim.

Beyond the automobile, Namikoshi sees applications for the design, with alterations, in scenarios such as heating water from waste heat in geothermal systems.

The following video shows a display test of Namikoshi’s 4-in-1 concept engine.

Source: Namikoshi Electronics (Japanese)

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29 comments
Adrien
um... is it me or does the vibration on that thing look awful... most engines have counter-moving masses / balance shafts etc etc so that the total nett movement of mass is always as close to zero as possible. Looks like they didn't even consider this for that engine. Also would have been good if that video showed an engine actually running off some actual fuel, rather than being driven by a cordless drill.....
David Hooppell
Also I don't understand how sufficient compression can occur without the vast mechanical advantage of a traditional arrangement toward top-dead-center..
Alex Haws
It's not just you, it's a terrible idea, that thing will shake itself to pieces eventually. Also, in terms of long-term maintenance, replacing bearing shells is a damn sight easier than those massive cartridge roller bearings - pretty much always going to be an engine-out job. Plus, a very important job of bearing shells is to absorb any metal particles (embeddability) to reduce wear on crank/rods - you won't get that with ball bearings, unless of course the bearing housings have a similar tri-metal makeup to bearing shells.
Martin Leitner
It's just ridiculous how many people are still trying to improve the ICE. Will they ever discover that they are riding a dead horse? The electric engine is by far superior to the ICE: - no emissions - better efficiency - better power to weight ratio - better torque characteristics --> doesn't need gear shifts nor clutch - better response characteristics - virtually maintenance free - quiet - recovers energy downhill or while braking
Threesixty
A crucial detail is missing...the big end of the crankshaft must be sliding in a vertical slot in the rigid con-rod/beam affair, not a pivot point as indicated in the comparison of the number of pivot points. A sliding joint is much more complicated than a simple round bearing. Why the massive crankshaft bearings? I cannot see a reason for them being so big.
Bernd
This is nothing else than a good old one cylinder engine with all it's unbalanced mass, only made more complicated with 4 combustion chambers, a vertical slot and huge bearings. What's radical about that?
Nicolas Zart
I can't help but find the irony of using an electric motor, itself far superior in efficiency to an ICE, to demonstrate an iteration of opposing Pistons extremely amusing. I'm not sure what the gains are here, short of a single rotor instead of a camshaft. It looks like a steam locomotive piston and wheel design. It might be a good time to work on battery energy density instead of making opposing pistons work better. Just a thought.
Baron TheRed
Well its true that a electric motor is far more simple and efficient than an internal combustion engine. However internal combustion engines are currently more practical because current battery technology can not replace the energy density and commonness of petrol. I hope in the near future batteries will be so cheap, energy dense and efficient that we can replace these freaky complex ICE's with big brushless 3-phase electric motors
Cyndysub
The world does not need any more ICE powered cars or insane levels of Horsepower that car companies continue to vomit onto the market for the benefit of the Fat Cat Oil companies.This is a company just wasting a lot of money and is going nowhere. It is a better use of time and money to do research only on electric cars and their batteries and get off of the petroleum merry go round that is ruining our environment. We have the technology to do this but some are spineless and lack the intelligence to see this. The Old way of generating energy for our cars and houses needs to be abandoned. The Status Quo is outdated and needs to be dumped in favor of more intelligent choices.
Misti Pickles
Yeah yeah yeah, all you anti-ICE freaks. Electric is cool, torque filled power. But you simpletons refuse to acknowledge that energy storage and transportation is so problematic and expensive that we HAVE NO PRACTICAL solutions. I have been a radio controled modeler since the 1980's, and while battery technology has created fantastic opportunities for models, seeing the few who have transformed this technology to flying airplanes have done so at a COST far outstripping what a common can afford. The promise for affordable battery technology is ALWAYS just out of reach, and has been for DECADES! So yeah, while you freaks tout electric power as the only thing worthy of research, it remains viable ONLY for the rich. Gas cars are inevitably cheaper per mile, when ALL costs are factored, and will remain so in the next decade or two . . .