Brake System Design and Optimization: Temperature Measurement
Watch This Course
$149 USD $74.50 USD
-OR-
Or
8 easy payments of only $9.31
Instant access. Easy checkout. No fees.
Temperature Measurement
10.53
| 00:00 | - In this section of the course, we'll be concentrating on the different measurements we can take for the braking system to help us understand how well it's working and where improvements can be made. |
| 00:11 | Considering how much time we've spent discussing the effects of temperature in the course so far, it'll come as no surprise that this is going to be one of the primary measurements we'll be concentrating on. |
| 00:22 | There are however a number of different ways we normally measure temperature in a braking system. |
| 00:27 | The first one to discuss is temperature sensitive paint that can be applied to the brake discs in order to understand their maximum temperature. |
| 00:35 | The working principle here is that the paint is applied to the brake disc and this paint is formulated in a way that means it changes colour at a pre defined temperature. |
| 00:45 | This can mean that multiple paints, each with a different temperature range are applied or alternatively, a single paint that the specific shade of the final colour can be matched to a reference sample. |
| 00:58 | In the case of using multiple paints, there are generally three colours used, green, orange and red. |
| 01:04 | In the case of the AP Racing brake temperature paint kit, which is one of the most commonly used, the temperature transitions for each colour are 430°C for green, 560°C for orange and 610°C for red. |
| 01:21 | When the respective temperature ranges are met, the green turns white, orange turns yellow and the red turns white. |
| 01:29 | In the case of a single colour paint, this kit from Genesis Technologies, starts off as red and changes to different colours based on the maximum temperature reached. |
| 01:40 | You can then use the supplied reference colour chart to determine the temperature. |
| 01:44 | The main limitation of this type of temperature measurement is that it only gives us the one single maximum temperature reached by the brakes over a given stint. |
| 01:54 | This limits its usefulness because we don't know where on track this maximum occurred or how far into the stint. |
| 02:01 | Using this type of paint to determine the operating temperature of the discs has been used in the motorsport industry for a long time. |
| 02:08 | As a result, it tends to be thought of as a bit of an outdated and old school method but the reality is that despite its limitations it's still a useful and commonly used tool today. |
| 02:20 | This is because while some of the real time temperature measurements that we'll be discussing soon give a fuller picture of what's going on, in some race series, these methods aren't allowed by the regulations. |
| 02:33 | Another restriction can be budget as some of these real time measurements can become quite expensive, especially when paired with a high end datalogger. |
| 02:40 | This means brake temperature paint remains a legitimate option today. |
| 02:45 | The next type of measurement is a temperature sensitive sticker. |
| 02:49 | You can see these stickers in use in many different applications, both within and outside of motorsport. |
| 02:56 | The basic idea here is that there's a graduated scale built into the sticker. |
| 03:00 | This scale is sensitive to temperature and as each temperature is reached, that part of the scale changes colour. Once that part of the scale has changed colour, it remains permanently changed and won't return to its previous state. |
| 03:16 | This means that if we're regularly experiencing high temperatures, we need to replace the stickers as required. |
| 03:23 | With brakes, these stickers are most often attached to the callipers, the main reason we want to monitor the brake calliper temperatures is to make sure we don't exceed the maximum safe temperatures of both the brake callipers, seals and the brake fluid. |
| 03:39 | As the brake fluid is housed within the callipers, this gives a good idea of the sorts of temperatures it'll be exposed to. |
| 03:45 | In a similar way to using brake temperature paint, the stickers are also a one use type of deal, once the maximum safe temperature has been reached and exceeded. |
| 03:56 | With that said, as long as we're not constantly exceeding these limits, the stickers provide an excellent source of information for both monitoring and diagnosing brake system problems. |
| 04:07 | If you get the chance to spend time in the pit lane of a professional racing series during practice sessions, one of the things you'll often see is someone walking down the pit lane, stopping periodically at different cars and holding a probe against a brake disc of each end of the car. |
| 04:24 | This is most often a technical representative from the brake supplier. |
| 04:28 | The probe they're holding is a thermocoupe and they're trying to keep an eye on the disc brake temperatures that each car has in an effort to understand how each team is using their brakes. |
| 04:40 | It's important that this temperature is taken as soon as the car arrives in pit lane and it's only really relevant if the car has come off track with the brakes still hot. |
| 04:49 | If there's been intentional cooling of the brakes on track before it came in, or a very long straight with limited braking between the last corner and the pit entry then there's little to learn. |
| 05:00 | Most often when people are checking the brake temperatures in this way, they tend to be more focused on the difference between the front and the rear brake temperatures rather than the absolute numbers. |
| 05:12 | By knowing the difference between the front and rear discs it's possible to diagnose braking stability and retardation problems and as you'll probably remember from the previous section of the course, the operating temperature of the disc can have a big impact on the friction characteristics. |
| 05:29 | By looking at the temperature differences, the brake company representative may make suggestions to the team on making changes to the amount of cooling to one end of the car or even recommending trying a different pad compound at one end to work in a different temperature range depending on the feedback from the team or driver. |
| 05:49 | The next type of temperature measurement to discuss is a contact type thermocouple that's fitted to each corner of the car. |
| 05:55 | This is a sensor that's in contact with the brake disc itself, constantly sliding across its surface. |
| 06:02 | The big advantage of this type of sensor is that we can start to understand the brake disc temperatures at all points in the track. |
| 06:10 | This is extremely helpful for understanding the real time temperature of the brake discs at each corner of the car and allows us to get a handle on problems with temperature splits and the rate of cooling. |
| 06:22 | One downside of this type of sensor is that it only gives us feedback for a single point on the disc radius. |
| 06:28 | This means any problem with temperature distribution across the disc radius can't be picked up. |
| 06:34 | This isn't necessarily a problem, it's simply a limitation to be aware of. |
| 06:39 | The final type of temperature measurement we'll be discussing is infrared sensors. |
| 06:44 | Usually referred to as IR. |
| 06:47 | These are non contact type sensors, the sensing element is simply pointed at the component of interest and mounted at a distance that's mandated by the manufacturer. |
| 06:58 | IR sensors can be used to monitor the temperature of anything of interest. |
| 07:03 | In some cases, they're used to measure the calliper temperature but most commonly they're used to understand the brake disc temperatures. |
| 07:11 | When given the choice, using an IR sensor is generally the preferred method for temperature measurements of brake discs. |
| 07:18 | Like most things though, the best option is often the most expensive and that holds true in this case. |
| 07:25 | IR sensors are available in either single point or in an array style. |
| 07:29 | A single point sensor is only capable of measuring over a relatively small area. |
| 07:35 | It gives a single output value of the temperature of that single point on the disc. |
| 07:40 | An array type measures the temperature at multiple points across the disc face and outputs a number of different temperature values to give us an idea of the temperature distribution. |
| 07:51 | This can mean receiving as many as 16 temperature channels from each corner of the car. |
| 07:58 | The advantage of an array type sensor is that it allows us to start understanding potential problems with uneven temperature distribution across the disc face. |
| 08:07 | This could be the result of the mechanical design of the disc or mounting bell, uneven pressure distribution on the brake pads due to tapering issues, or indicate an issue with the cooling method used. |
| 08:20 | While having an array type sensor does give us some more information about how the brakes are working, they do tend to be a lot more expensive than the single point sensors so with that in mind, a single point sensor is still an extremely useful tool and shouldn't be overlooked as a legitimate option. |
| 08:39 | In the case of both contact type and IR disc temperature sensors, these can be both recorded on a datalogger and sent over live telemetry to the engineers in the pit. |
| 08:49 | Looking at the logged data once it's been downloaded from the car is a big advantage. |
| 08:54 | Being able to see the temperatures live over the telemetry while the car is on track allows us to make decisions even quicker and within that same session. |
| 09:05 | Here's an example of some logged data for a car with a single point sensor on one front and one rear corner of the car. |
| 09:13 | Looking at the temperature evolution across the lap, along with the speed trace of the car, we can clearly see the temperature evolutions at both ends of the car. |
| 09:23 | We can see the spikes in temperature as the car is in the braking zones, the splits in the front to rear temperature and the rate of disc cooling as the car makes its way down each straight. |
| 09:36 | Here in this example, we're looking at the data from an array type brake temperature sensor with 16 channels. |
| 09:42 | In this case, we're only looking at the temperatures for one corner of the car. |
| 09:47 | By using a combination of time and distance plots, different math channels and other visualisation tools, we can start to understand the temperature distribution across each disc face. |
| 09:59 | If this is something you're interested in exploring in more detail, I suggest taking a look at our professional motorsport data analysis course which digs into brake temperature data analysis in more detail. |
| 10:13 | One last point about IR type sensors is that they must be matched in terms of both the temperature range and disc material type. |
| 10:20 | Each sensor is calibrated to a given temperature range and the emissivity of the disc material which is related to how much light is reflected from the surface. |
| 10:31 | In summary, there's a different range of temperature monitoring options available, depending on both your application and budget. |
| 10:39 | Regardless of the method you choose to measure your brake temperatures, each of the options we've gone through in this module brings benefits in understanding and tuning your brake package. |
