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.

About these ads

6 thoughts on “Motiv Releases Design of MkII Clarke-Brayton Engine

  1. Thank you for your effort on the development.
    How much is the power in HP of your engine developed.
    Also the power/weight, size and etc for the prototype.
    whta is your developnig schedule for commercial engine.

    Regards

    Hoon Heo

    • Hi Hoon – at 2200 rpm this engine should produce 146 horsepower. We do not plan on running it any faster than this, but the eventual commercial engine we hope to have a rated speed at around 3600 rpm for an engine of this size. This prototype was not designed to be light – It was overdesigned in an abundance of caution in many places, and also to make the monoblock (head plus block cast as a single piece) to be identical on both sides of the engine to reduce costs.

      • Dear Ed O’Malley
        I heard about your work from Glenna, sister of Prof. Stearman at UT Astin who supervised me while I was studying in U.S. last 1979~81.
        I am very happy to see you are doing a great job.
        Let me ask questions as follows
        (1)As far as diesel engine is concern, what is your solution to replace “CRDI” technique? Have you developed any alternatives or what ?
        (2) what is the dimension of the engine a’ssy?
        (3)Also what is your schedule of R&D or development?

        I am going to visit U.S from 1st through 11th of this July.
        Might there be any chances for me to visit your place and see your work?

  2. Until you can put it in a pick-up truck, it’s just another pipe dream like Ecomotors or Pinnacle. These are all great engines but putting them into production to meet the needs of the OTR industry is still decades away. This doesn’t even take into account the economics of large companies, Cummins, Navistar, of producing cheaper engines to undercut the new technology.

  3. I’m not in your industry, but am involved in the development of complex technology that has taken years and nearly $400M of seed money from private equity. Kudos to you for sticking to this and thinking carefully about the many variables required to generate this concept, make molds, and do the casting + testing. I trust you do well and can eventually commercialize this concept.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s