Here's my first , hopefully workable version of an active grillblock.
my top grill with the surounding pannel is a separate unit held in place with 3 bolts so i could build a separate "active grillblock" unit and swap the two when the active one's finished.
what i think will work best for me is a very simple system that keeps the grill 100% closed untill the fan comes on and than open in fully, thusfar i've only had the fan come on while stuck in traffic, wich occurs rarely so i can get aways with a full grillblock most of the time, but not always.
i've scratched my head over the simplest actuator, and where to get it, to for now i think a small electric motor might be the easyset... this will open or close the grillblock by rotating it and at both stops the door will press a switch to turn off power to the motor.
here's the scematic i think might work:
the"fan" wire will be linked to the fans power supply and thus only be powered when the fan is on, the 12v wire is always powered
R1 and R2 are two relays that are set up to switch the motor polarity and thus controle it's direction.
A is a button thats pressed and breaks the connection when the hatch is fully closed, B does the same then the hatch is fully open.
R3 switches between B and A
here's what should happen:
suppose the door is half open and we start the car,
A is not pressed so trough A, R3 and R1 the motor M is powered and will turn the hatch in direction A wich is will close it, when fully closed the hatch will press on swich A wich will interupt power to the motor. the hatch will remain closed (if not A not be pressed anymore and the hatch will reclose itself!)
now we get stuck in traffic, everthing heats up and the fan comes on,
this will cause R1 , R2 and R3 to switch R1 and R2 will change the direction in wich the motor will spin and R3 will override A so the motor is powered again trough the unpressed B switch... the motor will spin the hatch to it's open position until it presses against switch B wich will interrupt power to the motor again.
the hatch is now open and the fan is running.
things cool down as they should.
the fan cuts out, wich causes R1,R2 and R2 to return to their start position, this overrides B wich is still pressed by the open door, the motor will spin again in the opposit direction and close the door.
i've added two diodes to make sure the system doesn't shorts out when R1 and R2 don't witch at exactly the same time.
could this work, anyone has a better or simpler idea... i'd love to be able to build this if only for the "cool" factor of it
what i think will work best for me is a very simple system that keeps the grill 100% closed untill the fan comes on and than open in fully,
Why not simply add in a 2nd thermostat for the grill block?
If you are careful about the temp settings you get for the two thermostats (the new one, and the existing one), you could then have the grill block open when the engine needs cooling, but still at a lower (maybe 10 or 20 degrees lower?) temp than when the fan comes on. This effectively gives you three (automatically chosen) cooling options:
1) When you don't need cooling, the fan is off and the grill is blocked (as both thermostats aren't yet triggered).
2) When the 1st thermostat temperature is reached, the grill block opens to allow for natural cooling. This looses the aero gains from the grill block, but doesn't hit you with the high energy cost to power the fan.
3) On those occasions when even a fully open grill is insufficient to provide enough cooling, than the engine will continue to heat up. As the engine heats up, the 2nd thermostat will also be triggered, and the fan will come on in order to provide maximum cooling to the engine (but at the greatest hit to FE).