Automatic Tire Inflation System

thingiverse

Tire pressure is a measure of the amount of air in a vehicle’s tires, in pounds per square inch. Having the proper tire pressure is a crucial safety issue. While many people may not recognize it, tires are one of the most important safety devices on a car. It is advisable to check the tire pressure on all four tires at least monthly, if not more frequently – but this often ceases to be the case. As outlined by a NHTSA survey conducted in February 2001, 71% of the respondents stated that they check the tire pressure of their vehicles less than once a month. It is not surprising then, that AAA estimates about 80% of the cars on the road are driving with one or more tires under-inflated, leading to 1.2 billion gallons of wasted gas. There is a safety aspect to this issue as well: a government study performed in the United States has found that vehicles with under-inflated tires are 3 times more likely to be in an accident. While there might not be legal ramifications of not maintaining the recommended level of pressure, incorrect tire pressure will compromise cornering, braking and stability. And in the worst-case scenario, improper tire pressure can lead to tire failure — and a serious accident. Incorrect tire pressure will also affect comfort, fuel economy and tire life. To illustrate: if tire pressure is too high, then less of the tire touches the ground. As a consequence, the car will bounce around on the road. And when the tires are bouncing instead of firmly planted on the road, traction suffers and so do stopping distances. A decrease in ride comfort will also be felt. On the other hand, low tire pressure causes too much of the tire's surface area to touch the ground, which increases friction between the road and the tire. As a result, not only will the tires wear prematurely, but they also could overheat. Overheating can lead to tread separation, the seriousness of which cannot be undermined. Further, tire pressure can change – and does change – for a variety of reasons. Each time the car goes over a speed breaker, pot holes or other road surface irregularities, some amount of air escapes from the tires and the pressure decreases. Tire pressure is also sensitive to temperature - it decreases by about 1 psi for every 10-degree Fahrenheit drop in outside air temperature. The proposed design seeks to do away with all of these problems, by offering one simple solution – automatic monitoring and maintainenace of the recommended tire pressure of a vehicle. It is worthy to note that thanks to The Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act of 2000, all new motor vehicles are required to “indicate to the operator when a tire is significantly under-inflated.” The proposed design goes above and beyond this requirement of merely monitoring air pressure levels in a tire, rather it also takes action and fills compressed air in the case of under-inflation, and releases compressed air into the atmosphere in the case of over-inflation. Further, it does so in a periodic and recurrent fashion (for example, every 10 minutes or each time the engine is ignited) as opposed to the lackadaisical approach most drivers have towards tire pressure. The various components of the proposed design are shown, purely for representative purposes, in the first file that has been uploaded by the name of “Automatic Tire Inflation System (Representative Model)”. Each component has been marked with letters for reference and they are discussed in the same order below: A. Operator Control Manual: This would enable the driver or the operator to select from pre-saved tire pressure levels, to be best prepared for the current driving situation. B. Electronic Control Unit (ECU): The ECU is responsible for sending signals to the Pneumatic Control Unit (PCU), instructing it to ascertain the existing air pressure levels in each tire, and relay this information back to the ECU. Depending on the information obtained, the ECU will instruct the PCU to increase or decrease the air pressure in a tire. C. Pneumatic Control Unit (PCU): After checking each tire for its air pressure and sending this information back to the ECU, the PCU will work with the air compressor according to the second set of instructions received from the ECU. It will either deliver the required amount of compressed air to a tire, or remove the required amount of compressed air from a tire. D. Air Compressor (Electric motor + Pump): The compressor’s principal job is to provide and maintain a supply of compressed air, which can be delivered to an under-inflated tire as and when required. The air compressor has three principal components – the pump, electric motor and storage tank. E. Air Compressor (Storage Tank): The storage tank will be 3D printed, and hence has been shown separately as Component E. F. Pipes or Tubes: These pipes or tubes are needed to transport the compressed air from the air source, to the tires. Usually this objective is achieved by taking support from the axle. This component will be 3D printed. G. Check Valves: The check valves are needed to ensure that the recommended air pressure level can be maintained in each tire independently. In other words, when the air pressure level of one tire is being adjusted, the check valves prevent disturbing the air pressure levels in the remaining tires. These valves will be 3D printed. The second file, by the name of “Air Storage Tank (Scaled)”, is a model of the compressed air storage tank. It has been drawn to scale (1mm = 1 inch) and can hold 2 gallons of compressed air, which is an adequate level of storage for the proposed system. The average tire can hold about 9 gallons of compressed air. Considering that this system is able to keep the pressure levels within 5% of the recommended range, there should be a maximum loss of 0.05 x 9 gallons = 0.45 gallons in a tire before the system kicks in. For 4 tires, the total loss would be 0.45 gallons x 4 = 1.8 gallons. Hence, the 2 gallon storage tank. Additionally, the storage tank is not required to store the entire volume of compressed air needed for operation at any given point in time. It is meant to act as a reservoir which can be simultaneously replenished with compressed air from the pump during use. The third file, by the name of “Air Check-Valves (Scaled)”, is a model of the check-valve that will be used for this system. A total of 4 check-valves will need to be used (1 for each tire) for a standard passenger vehicle. It has been drawn to scale (1mm = 1 mm), with an inner hole of diameter 10 mm.