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  • Alternate exhaust valve lifting mechanisms

    Guys, I need some help here please. I am researching alternate means of opening i.c. engine exhaust valves other than with the traditional 2:1 gear train, and cam. I have so far found only four methods, and I don't know if its only my poor google-foo, or if there simply never were that many in the first place.
    I have found the star wheel mechanism, as found on early full size "gearless" hit and miss engines, the weird siamesed cam that flips a lever back and forth, again as found on some early full sized hit and miss engines, the small version adapted by Philip Duclos on his Gearless hit and miss engine (which looks a bit like a metal Swastika) and the strange cam arrangement patented by the Wright brothers of airplane fame. Does anyone know of any other strange exhaust valve opening devices that were totally mechanical and operated successfully to open and close exhaust valves?---Brian
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

  • #2
    What about the Ducati motorcycle Desmodromic valves?
    Kansas City area

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    • #3
      Sleeve valves as used in some aircraft engines.

      Rob

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      • #4
        Desmodromic valves actually require two camshafts. I am trying to completely avoid a camshaft.
        http://upload.wikimedia.org/wikipedi...C3%B3w.svg.png
        Brian Rupnow
        Design engineer
        Barrie, Ontario, Canada

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        • #5
          Originally posted by Toolguy View Post
          What about the Ducati motorcycle Desmodromic valves?
          They still use a a camshaft, although timing belt driven, to move the mechanism. Gearless but not exactly. I thought using an eccentric on the crankshaft and only using part of its movement in some way?, but I cannot quite see it.
          Gene

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          • #6
            Could you concoct a mechanism using a swash plate design... similar to as used in some stirling engines.

            Rob

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            • #7
              Food for thought:
              http://www.cvel.clemson.edu/auto/sys...ve-timing.html

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              • #8
                Maybe an axial engine like the Duke?

                http://thekneeslider.com/duke-engine...-axial-engine/
                Kansas City area

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                • #9
                  Saw a cam arrangement in the science museum, looked like a swash plate thing, i.e. vertical cam, one valve each side, peculiar but the thing must have worked
                  http://www.animatedsoftware.com/pumpglos/swashpla.htm
                  Sorry suggested by mr sleepy, apologies
                  Mark
                  Last edited by boslab; 07-20-2014, 05:15 PM. Reason: Not reading!

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                  • #10
                    Originally posted by firbikrhd1 View Post
                    I worked with pneumatic valve actuators a few years ago, its a pretty neat technology in that you can actively change the number of strokes/cycle and also simulate cam/valve lift profiles with some unrealistic openings/closings. Sadly, IIRC it was ~$100k/cylinder for the hardware.
                    "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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                    • #11
                      Great bunch of ideas, guys. I want to keep it totally mechanical, so that kind of lets out the electromagnetic and pneumatic systems. It also has to be something I am capable of building with my lathe and mill, with some expectation of making a running engine. I know beyond doubt that I can machine the starwheel type of system. I don't believe I could machine the strange double track cam with the equipment I have.
                      Brian Rupnow
                      Design engineer
                      Barrie, Ontario, Canada

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                      • #12
                        Originally posted by justanengineer View Post
                        I worked with pneumatic valve actuators a few years ago, its a pretty neat technology in that you can actively change the number of strokes/cycle and also simulate cam/valve lift profiles with some unrealistic openings/closings. Sadly, IIRC it was ~$100k/cylinder for the hardware.

                        Much along the same line of thought are the electro-mechanical valve actuators, basically a solenoid operated valve system.
                        I believe there was a build article a few years ago in either Home Shop Machinist or Machinist Workshop magazine of such an engine that utilized this camless valve actuation system.

                        Brian, try Googling "camless engine valve actuation" and see what pops up if you would like to pursue this method. It will of course open up a whole new learning discipline. Probably not what you want to hear.

                        PS:
                        OOPS! took too long making brunch and typing my reply....I see Brian wants to keep this totally mechanical.
                        Last edited by Willy; 07-20-2014, 12:29 PM.
                        Home, down in the valley behind the Red Angus
                        Bad Decisions Make Good Stories​

                        Location: British Columbia

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                        • #13
                          I was deep in thought one day over a software problem I had and was idly clicking my ball point pen in and out. It has a transparent barrel so I could watch the mechanism working. It is a set of rotating ramps with offset landings. It is also a mechanical divide by N mechanism. I've often wondered i what other ways it can be used and it occurs to me that it can control an exhaust valve in a fashion similar to a hit/miss engine, but with precision timing. It would still require a cam, but no gear. It doesn't have to be round, either.

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                          • #14
                            Hi Brian
                            How about something like this:

                            The shaft running through the head basically behaves like a pair of rotating ball valves. Since each valve opens twice per revolution it needs to run at one
                            fourth of the crankshaft speed.
                            Location: Long Island, N.Y.

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                            • #15
                              Originally posted by Willy View Post
                              Much along the same line of thought are the electro-mechanical valve actuators, basically a solenoid operated valve system.
                              I know that Brian willnot be interested in using the idea , but Keonisegg have an electro-mechanical valve SAAB running.
                              http://www.saabsunited.com/2013/02/k...echnology.html

                              Rob

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