Tech Briefs Create the Future Contest

Tech Briefs is the publishing arm of SAE international and publishes NASA Tech Briefs, Automotive Engineering and more. They are holding their annual Create the Future Design Contest and we have entered the Clarke-Brayton Engine! There’s a lot of competition on there, so we need your help! Please register and vote.  I know registration is a pain, it will really help us out! Here’s the link:

http://contest.techbriefs.com/2016/entries/automotive-transportation/6431-0422-230756-a-highly-efficient-compact-and-affordable-engine-for-use-with-diesel-or-natural-gas

Team in LB SMALL

A Highly Efficient, Compact and Affordable Engine

After months of analyzing test data, improving simulation code to better reflect what’s happening in the real engine and some design improvements, The ultimate performance of the Clarke-Brayton engine keeps getting clearer – and for the first time we can confirm that it can do all of this while meeting stringent NOx emissions standards using conventional aftertreatment systems.

A recent design improvement from the mind of Chief Scientist and inventor John Clarke improves power density even further:

On the left is a 359 horsepower Clarke-Brayton V6 compared to a 325 horsepower Cummins 6.7L on the right

On the left is a 359 horsepower Clarke-Brayton V6 compared to a 325 horsepower Cummins 6.7L on the right

Above is a comparison of a Clarke-Brayton Engine in a V6 configuration on the left putting out 359 horsepower compared to a 325 horsepower Cummins 6.7L I6 – both engines are compared at the same mean piston speed. In addition to the clear advantage we have in size and weight, the reduced amount of material will also reduce cost.  Further, the Clarke-Brayton Engine is naturally aspirated so the expense of turbos and aftercoolers are eliminated and only 1/3 the number of fuel injectors are required leading to considerable cost benefits.

A naturally aspirated engine has dramatically improved transient response, meaning when you depress the accelerator, the engine responds with more power and speed immediately, eliminating the so-called “turbo lag” suffered by virtually all conventional diesels.

The engine also shows a remarkably flat torque curve and extremely efficient operation at all conditions, as shown in the indicated thermal efficiency map below.

Indicated Thermal Efficiency Map of the Clarke-Brayton Engine

Indicated Thermal Efficiency Map of the Clarke-Brayton Engine

Peak indicated thermal efficiency is 59% (for you engine nerds out there, this includes gas exchange/pumping losses). More impressive is that efficiency remains well above 53% even in low-load, low speed conditions where vehicles spend most of their time operating.

Our friction model predicts peak brake thermal efficiency at near 55%, compared to 42% for today’s best automotive diesels.

This engine promises to have great benefit to a number of applications including heavy-duty and medium-duty trucking, automotive, marine and power generation. It’s ability to use natural gas as a compression-ignition fuel – the subject of a future post – further increases its attractiveness in a number of segments.  We’ve been talking to a number of interested potential strategic partners and are excited about finding the perfect relationship to help propel this technology to market.

Testing of MkII Clarke-Brayton Engine Yields Excellent Results

After many months and modifications to get the engine running smoothly we are finally getting great data!  Not only is the data itself high-quality but they are showing that the engine is performing excellently.  I wish I could present the detailed data, but unfortunately it is still confidential, but here is a chart of pressure vs. crank angle of all three cylinders with the units removed from the axes:

Crank Angle vs. Pressure in the MkII Clarke-Brayton Engine. The circles and triangles are every 5th data point taken from running the engine. The solid lines are the predicted results from the computer simulation.

Crank Angle vs. Pressure in the MkII Clarke-Brayton Engine. The circles and triangles are every 5th data point taken from running the engine. The solid lines are the predicted results from the computer simulation.

We’ve run the engine for up to 30 minutes continuously at full-power.  We’ve learned that the engine is in fact extremely efficient, cooling the engine is not nearly as big of a challenge as we thought it might be and that we can improve even further on our current design.

Since the beginning of the MkII project in October 2013 we have spent just $800k covering ALL expenses.  I’d like to see any other engine company be so cash-efficient! If we can accomplish this much with so few resources, just imagine what we will do when we raise significant funds and engage with world-class strategic partners.

Here’s a video from one of our longer-duration test runs.

3D Printing Combustion Pistons

My last post was about the machining of our “low pressure” pistons.  Our combustion pistons start out with a very different kind of fabrication process: Direct Metal Laser Sintering (DMLS).  It is a kind of 3D printing.  Believe it or not, finding a short, entertaining video about DMLS is difficult.  So instead please enjoy the least annoying video about the process I could find:

Here is what the parts look like just after printing.

HP Piston Apr 1 #2 AS PRINTED

This had to be printed because there are some internal cooling passages inside of them that traditional machining cannot make.  In mass production this is handled by making them in two parts and then friction-welding the two halves together.  For just two prototypes, that is not economical, thus we went with DMLS.  There is still a lot of machining and grinding to do before the pistons are done.  Eventually, they will look like this:

HP Piston RenderEdit: Here is a finished piston next to one of the blanks!

Finished piston next to printed blank.

Finished piston next to printed blank.

 

Piston Machining

Austin Jones at J.H. Benedict has been very nice to send us several pictures of our 4340 steel exhaust pistons throughout the manufacturing process. They are almost finished. There is still some grinding to do and some machining on the crown.  You can see they did the turning operations first on the lathe, and then machined out the inside of the piston. Bushings for the wrist pin will be machined and ground out of a bronze alloy and pressed in later.

4340 steel billet for the piston beginning the process.

4340 steel billet for the piston beginning the process.

First turning operations for the piston are complete.

First turning operations for the piston are complete.

Machining processes on the piston.

Machining processes on the piston.

Roughing out the inside of the piston on the mill.

Roughing out the inside of the piston on the mill.

The piston is nearing completion!

The piston is nearing completion! Lands and grooves are still to be ground, and the crown is still to be machined. Bushings will be pressed in later.

 

Have all the important inventions already been invented?

An article in today’s Wall Street Journal entitled “Economists Debate: Has All the Important Stuff Already Been Invented?” documents the arguments of two economists at Northwestern University.  Robert Gordon, the more famous of the two and someone who commands $20,000 per speaking engagement argues that all the inventions that can have a major improvement in standard of living have been made and as a consequence, the average growth rate in the U.S. will stabilize at half its historic rate of 2%.  Joel Mokyr takes the opposite position and points out that this same prediction has been made repeatedly over the last 150 years and it has always been wrong.

Thomas Edison - the greatest inventor of all time.

Thomas Edison – the greatest inventor of all time.

I must say I agree with Mokyr.  Gordon makes the argument that past inventions such as electricity had direct positive impacts on people’s  lives whereas new energy technologies should not be counted the same way since they are merely mitigating damage from previous technological innovation rather than directly improving lives. I think this is a very short-sighted analysis.  Looking at energy, the west has been dependent on countries that are hostile towards them for energy but at the same time desire the west’s money.  Today it is more clear than ever that this relationship has plunged the west into numerous wars where thousands of lives are routinely lost and an enormous drag is put onto the economy.  Our lives are so dependent on the energy we get from these volatile regions of the world that markets boom and bust with every hint of trouble or stability. Technologies like horizontal drilling, fracking and our Clarke-Brayton engine can eliminate our dependence on hostile powers for energy, ending the need for massive loss of life and continuous strains on our economy.  These technologies are directly and massively impacting the lives of all Americans.

Gordon rates the internet as a relatively low-importance invention, often asking people what would they rather give up, their iphone or the flush toilet and he says that smart phones are just a minor improvement over the original telephone.  But how many times have you heard people say, “What did I ever do before smart phones?”.  Smart phones are not just portable telephones.  They are a portal for instant access to virtually all human knowledge that you carry in your pocket.  You can get answers to questions as mundane as where is the nearest gas station or as obscure as what were the traditions of the Mayans to mark the summer solstice.  In the past information that required days of planning and trips to university libraries can now be obtained in seconds from the moment you realize you want to know it. The implications for business, governance, technological innovation and simple personal satisfaction cannot be exaggerated.  If I had to choose between giving up smartphones or the convenience of the flush toilet, I would give up the flush toilet.

The only way the U.S. will be able to continue to improve quality of life for the lower and middle classes will be through innovation. Our current standard of living has advanced to the point that industrial manufacturing jobs for all but the most complex products are often not sufficient to maintain Americans in the style to which they have become accustomed.  Entrepreneurship, science and technology driving new technologies and new industries is our best chance for continuing to grow our economy and improve our lot.

Sand Casting the Engine Block

I thought some people might get a kick out of seeing how the sand casting process that we used to make our blocks and crankcases works.  It combines a bunch of different manufacturing techniques from rapidprototyping (commonly called “printing”), casting and machining.  A mold into which the molten metal will be poured to make the engine block must be made.  It has outer walls that define the shape of the outside of the block, and it has “cores” that define the shape of the internal cavities of the part.  These are made out of sand that is held together with a binder material.  The way these are made these days is to use a laser-sintering process.  A computer-controlled laser hardens a thin layer of sand in the shape that is required for the core or mold part.  Then a fresh layer of sand and binder is deposited onto the just-hardened layer and the laser makes another pass, building up the part layer-by-layer.

Sand cores for the MkII Clarke-Brayton engine

Sand cores for the MkII Clarke-Brayton engine

Above you can see a variety of the sand cores and molds that were used for our engine block/head.  Basically, you need to have sand filling up all the spaces where you do not want metal.  Building the mold is kinda like building a “negative” of the engine.  All the cores are assembled together.

s_CIMG4708s_CIMG4712s_CIMG4713s_CIMG4716

Special coatings are sprayed on to improve the surface finish of the metal and ensure that sand does not stick to it.
s_CIMG4720s_CIMG4721

 

The cores you see assembled here will be passages within the engine block.  Some of these passages will be to allow the air to flow through the engine as needed.  Some will be for coolant to flow through making sure the engine does not get too hot.s_CIMG4722

There is a last piece that goes on top of the assembly you see above but unfortunately I do not have a picture of the whole mold ready for pouring.  In designing the mold, special care needs to be taken that the molten metal will be able to fill up all the gaps completely, allowing air to escape through vents as more metal is poured in.

After the metal cools and hardens, all the sand gets broken up and cleared away, leaving just the metal part!s_CIMG9663

That part is closely inspected using 3D scanners to ensure dimensional tolerances were maintained and x-ray scanners to make sure there are no internal cracks or other problems that cannot be seen from the outside.

Next the part is put in to computer-controlled machining centers that will cut away excess material and provide all of the tightly controlled dimensions, surface textures and other features that are required to make an engine work property!

Here is a video that shows a similar process being done for a different engine block.  This video was not made at the foundry that is casting our parts.

First Pour

Our first block has been poured at the foundry – ACTech in Freiberg, Germany.  I was tempted to title this post as, “It LIVES!” We have been working on computer models of this complicated part for so long, to finally see a photograph of a real block made of compacted graphite iron instead of 1’s and 0’s is very very exciting.

MkII Clarke-Brayton Engine block just after being poured at the foundry

MkII Clarke-Brayton Engine block just after being poured at the foundry

The block is now being prepared for machining, after which it will look much sleeker!  The bulk of our smaller parts are already out for quote and we anticipate beginning testing on August 1st.  Maybe I will save the, “It LIVES!” post title for when the engine is actually breathing.

Happy Memorial Day, everybody!

Motiv Releases Design of MkII Clarke-Brayton Engine

I have been woefully absent from these pages the last several months since we started the design effort on the new engine. I am excited to finally be able to share what the team has been working on so dilligently.  The MkII Clarke-Brayton Engine is the next step in dramatically reducing fuel consumption in trucks, automobiles and generators without increasing costs.  It is also the next step in developing a highly efficient compression-ignition 100% natural gas engine that can meet the up-coming greenhouse gas emissions regulations. This is a boxer configuration split-cycle engine implementing what we have come to call the Clarke-Brayton cycle.  The thermodynamics of this engine are virtually identical to our previous “CCI” design but are implemented in a much more conventional way.  Everything that we published in our SAE paper at the 2013 World Congress holds true for this engine, but many of the difficulties related to the old engine are resolved.

MkII Clarke-Brayton Engine

MkII Clarke-Brayton Engine

Section of the MkII engine

Section of the MkII engine

As with the previous design, in the MkII air moves sequentially through three cylinders, starting at the mid-sized cylinders at the top of the section image. This architecture allows us to achieve a 56:1 compression ratio leading to a 30MPa peak pressure.  It has far less surface area for heat loss than a comparable conventional diesel due to the very small bore of the combustion chamber. The small combustion piston area leads to lower forces on the crank than a conventional engine would have if it were able to reach similar pressures, reducing rod bearing friction compared to conventional architectures. A lack of net forces on the main bearings due to the opposing forces of the piston pairs reduces main bearing friction compared to conventional engines. It expands exhaust gasses all the way to ambient pressure before the exhaust stroke.  Gas transfer from one cylinder to the next is begun at equal pressures on either side of the valve, which keeps velocities low, minimizing pumping losses and eliminates blow-down. The power is produced in almost a 50-50 split between the combustion (central) and exhaust (largest) pistons.  There is a power stroke every revolution. All valves are actuated by overhead cams. Piston ring sealing is completely conventional, eliminating the dynamic effects of the old design and greatly reducing the reciprocating mass.

The major components of the MkII Clarke-Brayton Engine have already been released to the foundry for casting and everything else should be released for fabrication within a couple of weeks.  We will test this summer at a globally renowned engine development lab and I hope to have results to share shortly after that.

A team of just three people designed the MkII from a back-of-the-napkin idea to a fully developed test engine in 7 months.  Azra Horowitz and John Clarke have both put in herculean efforts to get this done in time despite a couple unexpected thorny technical challenges along the way.  I could not be more proud to be working with them.