Ducted Blade Rotary Engine (DBRE)

Contributed by THOUGHTFLOW Design

U.S. Patent no.: US 7,171,941 B2  

A Turbine for the Masses!

A rotating disc, sandwiched between plates having a series of divot like chambers, carries spinning drive plates with a lobe engaging each chamber sequentially.  The sweep of a lobe through a chamber is analogous to the motion of a piston or perhaps a positive displacement turbine blade.

In the illustrated topography, each drive plate lobe accomplishes two cycles of operation simultaneously.  Air is drawn in behind one sweeping drive plate while exhaust gases are pushed out in front of it.  The following drive plate will enter that chamber 60 degrees later compressing the fresh air while being pushed by the combustion gases of the power stroke.

The four events repeat every 60 degrees with each of the six drive plates engaging chambers both above and below the disc. The displacement of a 10 inch diameter engine is 259 cu. inches with 36 power strokes per rotation.  One of the beautiful things about the DBRE is as the size doubles the displacement increased eight-fold!

The table below demonstrates this phenomonon as well as very conservative power estimates:

Fuel Efficiency

1)      Thermodynamic-  each cycle is a separate process and can be optimized for efficiency.  The external combustion process can be stabilized with a normal fuel/air mix core [catalytic] and the power output adjusted with ultra lean bypass air.  This provides cooling of the hot section,  lowers the combustion temperature and NOX emissions.  The inter stage heat energy is usefully recovered in the power stroke.  Metering the volume of combustion gases allowed to expand in the power stroke effectively lowers the heat wasted in exhaust. It is anticipated that a high ‘compression ratio’ can be maintained for thermodynamic efficiency over all operating parameters.

      2)     Losses eliminated-  some internal losses are inherently reduced by the low part count but more significant is the elimination of pumping loss. Conventional engines are throttled but must still carry enough momentum to complete all four cycles.  This forces the engine to work against itself and requires a high speed idle.

In contrast, the DBRE has staggered power strokes meaning there are no dead centers and they overlap the demands of the compression stroke.  Idle is unnecessary and pumping losses are gone.

    3)      Energy conservation-  Combustion (and fuel consumption) is restricted to the demand for power. While slowing down, fuel burn is stopped and regenerative braking energy is stored as compression for later use.  Captured internally, or with additional external accumulators, it can be released to motor the engine without combustion then fuel can be added as necessary.  Self starting.

Wide market potential
Our participation in the X-Prize event hopes to promote interest of other engine markets.  The need for cleaner power tools, lawnmowers, portable generators may be addressed with a low cost alternative.  High power density is needed for weight sensitive or small devices.  manufacturers of aircraft power plants and micro generators will have an interest. The technology of positive displacement as function of rotation applies to pumps and compressors.  The ability to passively switch the sequence of each chamber input or output from parallel to series make this a unique opportunity to disrupt a very wide market range.

The volume displaced by a Drive plate sweeping through chambers: 

'Exploding' view of the DBRE in motion:

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