Tire temperature sensor

Rubber Chicken
Posts: 2
Joined: Tue Dec 20, 2005 6:47 pm

Tire temperature sensor

Postby Rubber Chicken » Tue Dec 20, 2005 7:26 pm

This is a brief how-to on adding an infra-red tire temperature sensor. I do not have time to go into detail about the wiring, but if anyone is doing the same thing as me this will help. Cost was about $180 per sensor, with another $75 per display. The setup is not perfect - see the end of the post.

The sensor I used was an Omega OS136-1-mV This outputs 10 mV per degree F (or C with a different part #), and is easy to wire up. I mounted the sensors in the center of each front wheel, because the problem I was looking at was overheating front tires.

I used a Martel DPM2000 4 digit LCD display, but it would have been easier to use the DPM2000S so that I could use the same power supply to the DPM2000S and the OS136 - with the DPM2000 non S, you need to use a DC-DC converter to isolate the power supplies. Anyhow, setting jumpers on the DPM2000 gives you a direct temperature reading from the OS136. The jumper settings on the DPM2000 were not well documented. Anyhow, once I wired them together I had a real time tire tempature readout in the car.

It then wired the OS136 output into the DL1 analog 1 and 2, sharing an analog ground. In the software I setup a custom variable with the equation of VAR_XX / 10 Now the DL1 records and graphs the tire temps.

After a race weekend I found several interesting things. First, because I mounted the sensors in the center of the front wheels, turning the wheel gave a different reading. Solution to that would be to mount the sensor on the hub, but I'm happy with the center mounting because I'm interested on temperature over the course of a race, and can plot the temp at the same point on the track each lap. Second, the surface temperature rises and falls very quickly. eg a 80 degree F rise in 5 seconds on the outside front tire. Likewise the tires can cool at 50 degrees F in 5 seconds (the cooling curve is actually exponential). The tires reached some sort of equlibrium after only 3-4 laps - although it was highly dependent on how hard I was driving.

The problem I was diagnosing actually turned out to be a bent upper suspension arm changing the toe so that the front tires were toed out under power, and overheating. Tire temperatures (for me at least) do show up suspension problems.

ewaher
Posts: 41
Joined: Sat Nov 19, 2005 10:04 pm

Postby ewaher » Wed Dec 21, 2005 6:03 am

You can weld a small pipe in front of the tire off of the knuckle to get tire temps as the tire turns.

Great post though, very helpful.

Support

Postby Support » Wed Dec 21, 2005 9:59 am

...all interesting stuff!

Thanks for the post.

Support

David Ferguson
Posts: 25
Joined: Tue Jul 11, 2006 2:45 pm

Another solution

Postby David Ferguson » Tue Jul 11, 2006 4:16 pm

We use (and sell) the IR temp sensors from Solid State Racing, http://www.solidstateracing.com/osc/catalog/ When measuring tire temps from the front of a fendered car (especially one with little suspension travel like a sports racer), consider mounting the sensor above the wheel on the steering axis. The tire does not move in/out that much, and the mounting is greatly simplified.

The SSR sensor takes 5V power, and produces a linear voltage output of temperature from 32 degC to 150degC. Easy to use with a Race-Technology system.


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