The GoTek engine is actually quite simple and a puzzle when just looking at the line drawings. With a read of the patent it can be explained simply. GoTek Energy has their patent issued and the press, including some major media have noticed, including some of those line drawings to confuse folks. This is an engineering team to take note of, this concept may well be in your car of the future.

GoTek Engine Fig 5.  See text for details.  Click image for the largest view.

GoTek Engine Fig 5. See text for details. Click image for the largest view.

In Figure 5 the inventory of important parts are the outer circle and the innermost gear that are both non-moving parts. There is a roughly X shaped frame work, four gears at the ends of the crankshafts, four connecting rods that can barely be seen at compression and exhaust positions and four hinged flaps that make up the moving parts. That practically gives it all away.

Following the fuel and energy at the upper left into a cavity between the outer circle and the retracted flap intakes the fuel and starts the cycle. As the framework turns clockwise to the compression position at the upper right, the flap is moved out from the barely seen connecting rod that moved as the crankshaft gear pushes the connecting rod to the furthest point out. Now the fuel mix is ready for ignition.

The energy from the burning fuel’s released expanding gas pressure and heat pushes the flap back to the centerline. The energy flows through the connecting rod into the crankshaft whose gear tries to transmit it to the center stationary gear. But, the force of the energy is applied to the rotating mass of moving parts instead. When the fuel charge goes off the flap and connecting rod are moving inward turning the crankshaft journal in a half rotation pulling the framework and all the moving parts a quarter turn around. That’s the power stroke.

Momentum takes the framework another quarter turn as the crankshaft has turned another half turn and pushed the flap fully out again to complete the exhaust. Once explained it really is simple. This happens four times with each framework revolution.

What makes it confusing is the triangular shape of the combustion chamber, four crankshafts turning in a framework that also turns within a simple tube housing. Its like the expected cylinder block, crankshaft and pistons were turned inside out! That about what has happened.

GoTek Engine Fig 3. See text for details.  Click image for the largest view.

GoTek Engine Fig 3. See text for details. Click image for the largest view.

Figure 3 clarifies the connecting rod and crankshaft designs and makes the energy flow and motion more clear. The framework now looks more like a rotor and the end caps seem to be rotating parts as well as simplifying the sealing and extracting the lubricating oil.

Another point of great interest to those who have owned the famed Wankel engine is the rotating end caps greatly reduce the seal wear. A Wankel rotor side seal swept the entire sidewall but here the flap side seals need only sweep the distance of travel. That’s not much at the hinged end. Also the seal between flaps is a simple sweep in a true circle.

The GoTek looks to be naturally well balanced. The only reciprocating parts are the flaps and connecting rods that are counterbalanced opposite to each other. The engine should be very smooth indeed. With all four “strokes” completed in one revolution the smoothness will also be enhanced.

When Mazda brought the Wankel to market we were all impressed by the smoothness and the power to weight ratio. Efficiency and seal life did the engine in, but for those of us who had RX4s or Cosmos or RX7s, the memories are sweet, sweet indeed.

Some major manufacturer(s) is (are) likely to bite. Assuming the emission requirements can be handled the low production cost projections, efficiency and great size and power to weight potentials are sure to be very attractive to buyers.

Your humble writer has only one concern, that is the pumping losses on the flap side opposite of the fuel. Presumably the air will shift inside the rotor framework at a low energy cost.

Congratulations are in order for the GoTek Energy team. And a bunch of good luck too.


5 Comments so far

  1. Jon on June 27, 2014 9:46 PM

    Two concerns.
    Centripetal (or old school centrifugal)force will tend to push the flaps outward, causing a loss in high rpm power; there’s a breakeven point where centripetal force will equal inward force from pressure and the strength of the connecting rod.

    Cooling: There is no way to cool the inside of the flap piston other than oil splashing or high air flow.

    Fewer moving parts? Only if compared to a 4-stroke engine! There’s 4 cranks, 4 conrods and pins, 4 pistons/flaps; the only things missing are the valve train parts. A two stroke or turbine has even fewer parts and can be made just as efficient and ….have there been any emissions numbers, or power numbers on the new engine?

    Nest issue: same as a 2-stroke engine; the shape and placement of the ports and the timing or movement of the flaps will be critical. The flap will only be just descending as it passes the intake port and must be fully seated far enough in advance of closing the intake port to fully fill the combustion area. Same in reverse for exhaust. But, this means that for every revolution of the whole engine, the piston flaps must move in and out 4 times. This means a vibration rate equal to that of a valve on a diesel 2-stroke. The length of movement will be a compromise between power and torque.

    I agree with the crankcase air movement issue, as well as centrifugal oiling issues.

    Engines are complicated, and it never hurts to take a stab at improving what we have. But the proof will be in the performance, put one in a race car.

    Second to last thing; this article was written like the rotary engine is dead, which is hardly the case. The latest generation of rotary engines is quite powerful and the seal issues have been mitigated. The problem is, if you take a look at the RX-8, efficiency is just not there. Power equals fuel burned, add to that the emissions requirement from the EPA (at least for gasoline)and you have an almost mandated maximum efficiency.

    The trick has always been to make the most Useful energy for the fuel burned. The old hit n miss engines were slow and not super powerful, but they could make low RPM monster torque all day (with lots of bad emissions). Modern 4-strokes and diesels also make useful power. The only way a turbine makes useful power is through a massive gear reduction and ensuing power losses or mechanical failures (think indy car from the 60’s). If this engine is to make useful power, it’s output should fall within the 0-5000 RPM range. Because the flaps are vibrating 4 times the rate of the output, max RPM might be too low. Simple calculation: say the engine is spinning at 2000 RPM, flaps vibe at 8000 times per minute, which is 133 times per second. Throw in the g-forces and assume length of travel on the far end of the flap, and the ensuing torque from the rapid pivoting, and the forces will add up fast.

    Lastly, editing and proofing is a must. “that is the pimping losses on the…” Pimping???

  2. Brian Westenhaus on June 28, 2014 12:59 PM

    Thanks! The pimp now pumps. Your thoughts and critiques are quite welcome, any more?

  3. Charles on October 1, 2014 9:03 AM

    Not too worried about pumping loss on the crank case side, as the internal volume should remain the same. With two flaps compressing and two flaps retracting. More importantly is the use of frition reducers and scavenging, oil recovery from the crankcase posses a unique challenge.

  4. Scott Farrenkopf on December 17, 2014 11:45 AM

    GoTek Energy, Inc. appreciates the enthusiasm as well as the critiques our DynaKinetic rotary engine design has generated in your article. Taking into consideration feedback from technical sources is something we always feel is important.

    We want to say that “New Energy and Fuel” did a very nice job of analyzing our initial base architecture patent to clarify our engine’s operation. It inspired some great thinking and comments as well from your readers.

    We felt it was important to take some time to respond to Jon’s detailed comments about our engine.

    On the issue of centripetal effects versus RPM, from a power standpoint the force acts to aid on compression and exhaust cycles (BDC-to-TDC movements). In contrast and as noted, it acts to hinder on intake and power cycles (TDC-to-BDC movements). From an energy standpoint, there is balance. From a force and stress standpoint, intake and power cycles do need to consider the increased tension forces created on the rod and our points of rotation. Key points to note are that our rods are 1 piece with no bolted end caps and advancements in the rotation point robustness have occurred. Although our engine has centripetal influences which many other engines do not, it should be noted that our reciprocating mass is significantly less (over 70% less than a piston engine) which yields major gains as RPM increases!

    On the issue of pivot piston (flap) cooling, our pivot piston’s underside oil cooling is no different than a piston engine other than slinging it to the underside is easier.

    On fewer moving parts, we have a significant reduction compared to a piston engine. The number of moving parts in a valvetrain is significant. We have none of that. Granted we have more than a Wankel but compromises on torque and efficiency were made to achieve the Wankel’s 1 moving part. Likewise, the turbine has an open combustion chamber and needs very high RPM to achieve the best efficiency of any engine but at high cost and without motor vehicle applicability.

    On efficiency of other engines, the turbine is great at high RPM and altitude but not for ground based vehicles. The 2-stroke has emissions issues and that’s exactly why we do not see it in mass use today and in most cases it is being replaced with 4 cycle engines where it does exist.

    On ports, the relative placement of intake and exhaust ports do control overlap. The circumferential length determines duration. The shape determines lift. These are important tuning factors but they are no more critical than the tuning of a piston engine’s cam. We can do it with a sleeve. Additionally, the cam’s mechanical timing relation to the crank is no different than our rotor/piston’s mechanical timing relation to the ports.

    On vibration and pivot piston movement per main crank rev, our mini-cranks move at twice and not four times the speed of the main crank. A piston engine has 2 of its 4 cycles executed per main crank rev. The DynaKinetic engine has 4 of its 4 cycles executed per main crank rev. It should also be noted that 180 degree opposing pivot pistons are always perfectly balanced no matter where in operation they are at.

    On crankcase pressure, there is balance with high flow passages between chambers below the pivot pistons so there is no issue.

    On oiling evacuation, there were challenges to consider and we have addressed those with the right design features, leak path controls, flows, and dry sump oiling system.

    We agree that testing in application is the proof and we continue to progress to achieve those goals. Completion simply takes time and money.

    In summary, we agree the rotary engine is not dead and there are many great things happening on the internal combustion engine front. Stayed tuned as we make a difference with DynaKinetic power!

  5. Brian Westenhaus on December 17, 2014 10:00 PM

    Thanks Scott. BW

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