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Electro hydraulic valve

  1. Aug 3, 2006 #1


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    The auto industry will be using this method to contol inlet and exhuast valves, i think 6000 rpm is the limit so far with a 48v (coil), this system has many advantages ie variable valve timing/ dwell, what are the limitations of this idea and could it be retro fitted to cam shaft engines?
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  3. Aug 3, 2006 #2
    It would be an awesome improvement because you would have basically infinite valve timing which means max power over the whole RPM range. I guess it would also remove the need for a cam shaft and reduce the extra HP neede to turn that. I wonder what kind of HP engines this system will be used on. I know if you build a 700hp race engine, the valve springs pull the valves with about 600 lbs of force. You think a 48v coil can hold a valve with that much force?
  4. Aug 3, 2006 #3


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  5. Aug 3, 2006 #4


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  6. Aug 5, 2006 #5


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    I've seen one of the Lotus experimental engines running using this system.

    One of the drawbacks I was presented with was that each actuator cost around £18,000. On a sixteen valve engine that would soon add up.

    Obviously economies of scale will bring this down, but the technical limitations of such a system are reasonably insignificant. (There are also minor issues around packaging and control.)

    One of the things I found interesting about the system was that an effective Miller cycle could be employed just by altering the valve timing.

    In terms of retrofit, I doubt we'll see much. The advantages you'd gain from being able to use some funky timings on your existing car engine would be small compared with engines developed specifically to use such a system (with optimised breathing, bowl shape etc).
    Last edited: Aug 5, 2006
  7. Aug 5, 2006 #6
    The Ford PowerStroke diesel (actually the engine is made by International) uses something similar to this for fuel injection. There is a high pressure oil pump which pumps oil into galleys in the head. Through a plunger configuration in the head the fuel is put under this high pressure also. There would be one plunger per injector. The timing is done electronically. A solenoid valve opens (part of the injector) and lets the fuel into the combustion chamber. The voltage on the solenoid is slightly over 100 volts I believe. The time the injector valve is held open is determined by how far you have your foot into the pedal.
    Brewnog, I don't see why you couldn't retrofit existing engines with the system. Most of the guts are going to be integral to the head except the oil pump. Someone is likely to come up with heads like this for large displacement engines of the past.
    Triden, it's not the coil that holds the valve open. The coil operates a valve which allows hydraulic pressure to open the valve.
  8. Aug 5, 2006 #7
    Hello folks,

    Great topic. EHVs have been the state of the art for commerical aircraft "fly by wire" aerodynamic control surface actuators. Their precision of control is quite high, which makes performance tuning very fine.
    This is true. On a fly-by-wire actuator there are actually two coils that operate two valves in parallel. One coil is a shutoff (On/Off) valve that provides high pressure hydraulic fluid to the actuator's second stage valve, the EHV. While the shutoff valve is simply operated by 28VDC On/Off, the EHV is commanded dynamically (closed-loop) via a PCM electrical signal format.

    Using EHV for auto engine valves will obviously allow much tighter engine control and performance tailoring. It will be like going from stone knives to razors & lasers. :cool:

  9. Dec 22, 2008 #8
    Cars now are characterized by very powerfull systems and a crucial role is played by hydraulic check valves. They should be always very clean otherwise all the system will have serious problems. I think also Lotus cars have in their hydraulic system this kind of valves.
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