Study Finds Warmer Climate Could Stifle Carbon Uptake by Trees
President Obama Awards $2.3B for Tax Credits for New Clean-Tech Manufacturing Jobs; GE Gets Largest Battery-related Award

Opposed-piston Engine Company Achates Power Closes $19.2M Series B Round

Achates Power, a company developing a new family of opposed-piston engines, has completed a $19.2M Series B round with the addition of a new investor, Triangle Peak Partners. Triangle Peak joins the company’s existing investors: Sequoia Capital Partners, Rockport Capital Partners, Madrone Capital Partners, and InterWest Partners.

The Achates Power engine architecture is modular and scalable to address a variety of end-use applications. With more than five years of dynamometer validation of its single cylinder engine, the company is now testing a 4.2L 4-cylinder engine that rivals conventional engines nearly twice its size, according to Achates.

The A40 engine, as presented by Achates Power president and CEO David Johnson earlier in 2009, is a two-stroke compression-ignition engine, with high efficiency and high power.

Founded in 2004 by National Academy of Engineering Member, Dr. James Lemke and the late John Walton, the company has assembled a team of engine design and development experts from around the globe including a world-class Technical Advisory Board. CEO Johnson, is an industry veteran with more than 20 years of experience leading engine development for automotive and commercial vehicle industries around the world. The company has generated 8 US Patents with nearly 300 claims, 2 international patents, 10 US Patent Applications, and 31 National Phase Filings in numerous jurisdictions.

We believe that one of the solutions to our future energy needs is to do more with less. Achates Power is a novel company with innovative technologies that do just that. We are confident in the company’s ability to deliver a revolutionary engine that breaks barriers in fuel efficiency, power density and cost. We look forward to using our technical background and finance experience in connection with the Achates board and current investors to help Achates grow and succeed.

—Dain DeGroff founding partner at Triangle Peak Partners and new Board Member of Achates Power




Any efficiency numbers around?


There was another company that did an opposing design and they had less complex linkage, they got a government contract the last I heard.

There are no efficiency numbers because they are not all that much better. They have just made a better mouse trap as far as they are concerned, so no sense cluttering their promotion up with all of those little facts.

Tim Duncan

Looks very interesting concept. Some good efficiency potential from: Excellent breathing, so low pumping losses, layout give natural scavenging, the tangential ports shown could give mixing and charge dynamics to help combustion. Potential for very large expansion ratio. The friction and reciprocating mass in the valve train is avoided. No side loads on pistons, so less recip mass and friction per piston. However the 2 piece rods are ugly, more recip mass and some additional windage although windage is minor issue. The 2 crank friction losses are not much changed from one big crank, factors being oil flow, surface speed & area along with power output.
Package is the real inovation, the old aviation engine had all this but an odd pancake shape. If this was such a great idea why did it not take off in applications that could accept the odd package? Don't be scared off by 2 cranks, the forces should be timed and sized in perfect balance. Might be good in a commercial application? No valve and train loses, cost, maintenance or rev limits. Cost save in block heads and V-train is offset a little by added rods, crank. Then there is exhaust after treatment cost?? Maybe no different than The exhaust side, piston, rings etc is going to run much hotter and present some limiting issue. This may be compensated with piston cooling oiljets on that side. Scarry looking rod structure, a little to radical for my tastes, but this is mostly a design detail, only slightly a concept issue. Other curious features are the long piston skirts, this seems very counter intuitive with no side loads. Also the hollow rod than connects the piston to the truss rod.

Tim Duncan

Can anyone with Dynamics backround way in on the rotation direction of the cranks. I am thinking they would need to go opposite to keep system in balance?? That could complicate the power merging gear train.

Tim Duncan

No varialble valve timing tricks to help over wider load/rpm range. So again maybe well suited for constant speed and relative constant load.

Nick Lyons

@Tim D:

Long piston skirts are necessary to keep cylinder ports covered at TDC, I believe. Valve-in-head 2-stroke designs with ports that are opened by piston at BDC have the same issue.

Tim Duncan

@ Nick;
Thanks for that insight, I bet you are correct on this engine. I am used to seeing the intake port uncovered by the piston skirt in hi rev'ing 2 cyle engines. Snowmobile, leaf blower etc. They use this to get the intake mix into the crank case, as there is not lube oil. This appears to have some kind of oil sump (shape of the lower housing). So it all fits.

Roger Pham

>>"Any efficiency numbers around?"

Right off the bat, I can think of 10 percentage points gain (out of 100 points total) in thermal efficiency: Opposed piston reduces heat transfer to the cylinder's head. That's worth 8 points gain in efficiency. Then, the lack of piston side load is worth another 2-3 points gain.
So, for a typical turbocharged diesel engine having 45% peak thermal efficiency, adding to it 10-11 percentage points to that would raise the thermal efficiency to 55-56% efficiency. A very worthy gain indeed.

Roger Pham

What I meant is that opposed piston engine eliminates altogether heat loss to the cylinder head, since there is no cylinder head to speak of!

The two-stroke cycle allows low-temperature combustion without having to resort to ridiculously high boost to maintain power density, thus facilitates emission control problem without expensive post combustion emission control.

Roger Pham

From the picture, it appears that the cranks rotate in opposite directions. This would require two idler gear discs between the two cranks to merge the two cranks. Not much of a complication to achieve mass balance.

Variable valve timing is not as important in a diesel engine as in a gasoline engine, since diesel engine does not run as fast as a gasoline engine. Exhaust and intake valve overlapping always occurs in a two-stroke engine, but, since the fuel will be injected later, no loss of fuel out of the exhaust port will occur.

Roger Pham

Correction on the efficiency estimate:
at ~50% thermal efficiency, a 8% saving in heat loss will result in a 4% point gain in efficiency. So 45% + 4% + 2%=51%. Not bad.

Tim Duncan

I agree with you this is a very interesting concept. I wonder why it has been so long in dyno tests with no real efficiency numbers published. Having been involved with engine development and it can be full of pit falls. I showed it to guys at work and they said oh ya, looks a little like the old Faibanks Morris two stroke low speed engines. Just don't know of this weight and packaging optimization are enough to overcome what ever it has been that has kept this concept out of the main stream for so long. Am I missing some other factor or inovation that will change this?

michael timling

hmm..Im no expert at this but you guys are talking about heat loss. Both the crankshaft and piston sides will cause double contact area, but they only move at half the speed so the heat loss caused by friction should be 50%. I have no idea how much heat loss is (in percentage of the total )It sounds like a 4 % percent gain caused by 50% friciton loss is the same as 8% total gain. In any case, does that mean that a 4-split opposed piston engine would have a 75% friction loss according to the same principles? That means 45 +6+2 =53% efficiency? By the way...consider the looks of one of those red support under the car but with a cylinder on top as well, with 4 arms in each direction with a 4 split piston like a ball in the middle. That is what enginges will look like in the future. maybe...not

The comments to this entry are closed.