Arduino controlled actuated grill block

[wyatt]

Hi David,
I for one hadn't heard your idea, and I must say I like it. I think it may work as a partial grill block for low speeds. My only worry would be that the reason you don't need as much cooling at higher speeds is because you get so much more air flow around your radiator, and that removes the heat. If you were to block the entire grill at speed you may run into overheating problems. Perhaps half of the grill could be actuated, and the other half could be blocked with the spring. This would be easiest in cars like mine with two openings in the bumper.

[davidgrey50]

Two openings might work even better, as you could put a different rate spring on each for a two-stage blocking - flap 1 with a weak spring to close one opening for fairly fast, and flap 2 with a stronger spring to close the other opening for way fast. Of course, a flap could cover only part of a grille opening.

[donee]

Hi All,

What about using bellows, like from a linear table of a machine tool. There would be constant actuation load versus speed and position. So, you could run it back and forth with a cord and pulley turned by a motor.

The other device that would not have load variation with speed (or much) and position would be Basjoos's rotary door (PVC tubing with slot). This could be activated by solenoids if sectioned off, or a 1/2 turn rotary motor.

[skyl4rk]

Another way of getting the Arduino to do the job of sensing temperature and moving a grill block is to use a thermistor and a servo. There are some good how to's on the Arduino site. It will take a little programming. One way would be to connect the thermistor to the 5V output, and get a numerical "voltage" reading from the analog input pins on the Arduino. (sorry I am forgetting the correct terminology). Tape the thermistor to a coolant hose or otherwise put it in place to measure temperature and note the numerical voltage reading when it reaches your desired switch point. Then just program the Arduino to move the servo to the appropriate location as the thermistor voltage value changes. Different servos use different scripts but there are plenty of how to's on servo's. They can run off of the Arduino 5V output.

[Tango Charlie]

Radio control model aircraft use many various sized servos. A retract servo for a quarter scale model would have plenty of torque to actuate a grille block door.

[dcb]

It looks like daox has sorted out the arduino controlled actuator pretty well for his purposes

A vacuum actuator might be a good choice too (borrowed from a boneyard cruise control or heating system?)

[dustybarn]

Your grill block mechanism looks very nice! I've noticed this winter that the coolant temperature in my Smart swings wildly when the ambient temperature is low - a perfect application for a grill block.

I'd suggest basing its control algorithm on ambient temperature rather than on coolant temperature (perhaps with overrides at low and high coolant temps). For example, the shutter might be fully shut at 30F and fully open at 100F, varying in between. The exact calibration would require experimentation. That way the grill opening would always be "just right" for the ambient temperature rather than being oversized at everything other than the maximum expected air temperature.

One could even consider a vehicle speed input so that the shutter gradually closes as speed increases.

[diesel_john]

My caravan has auto trans, ac, and power steering, each of which has its own cooler and temperature requirements so there are areas of the grill that I must leave open after the trans. warms up. The newer vehicles have a grill designed to "stall " (aerodynamically) as the wind speed increases thereby automatically blocking the air flow proportional to wind speed over the grill. My biggest problem is the converter clutch won't lockup until the trans. is up to temperature.

[Daox]

This weekend I made a small update to the project. I put together my RBBB (really bare bones board) arduino kit. This will be what will eventually be used in the car after all the tweaking is done.

dustybarn, I don't see why an ambient temperature sensor would have any bearing on the actuation of the grill block. The only thing I care about is not getting the coolant too hot so the fan doesn't turn on. Yes, ambient temp is going to affect that, but I don't actually care about ambient temp, just the coolant temp. I still want the car to warm up as fast as humanly possibly even if its 120 degrees F outside. Only after it is up to temp should the door open up.