ESTIMATION OF INERTIA MOMENT OF CAR ENGINE MOVING PARTS

Problem. To calculate the car dynamics, especially in urban conditions with frequent transitions to lower gears, the values of the inertia moment (MI) or the equivalent mass (EM) of the engine moving parts, brought to the crankshaft, are required. However, they are not given in the specifications, and the known methods of measurement are both too complex and laborious, or not suitable for some vehicle types. Goal. To create a method for estimation the engine MI, suitable for all types of vehicles and not requiring special equipment or excessive time, labor or expenses. The method proposed: to measure MI of driving wheels and transmission with known methods. To lift the car with jacks aid until the driving wheels come off the floor. To speed-up them by the engine repeatedly, recording the acceleration parameters, for example, by video filming the speedometer and tachometer readings. To remove the driving wheels and repeat the speeding-up in the same gear and, if possible, with the same fuel supply rate. Using the videorecords, to calculate the average acceleration in these modes and MI of the engine using the formulas given. Methodology and results of the method verification. According to GPS signals the speedometer of the car Honda Civic 2006 was calibrated. EM of driving wheels (2 × 10.49 kg) and transmission (5.4 kg) was measured by the known methods. 24 accelerations with wheels, followed by 20 ones without wheels were carried out. The interval of more or less stable acceleration (86...97 km/h) was common for both modes, where the average acceleration with the wheels was 2.6469 m/s2, without wheels –3.8792 m/s2. Then EM=39.664 kg and MI=0.1782 kg•m2 were calculated, which is in the range of known values for engines of similar volume. However, result variation is too large. The ways of method improving: to reduce and stabilize the acceleration rates, for example, putting an abut under the gas pedal; increase the number of samples. Scientific novelty: the method of estimating the car engine moment of inertia has been proposed and tested. Practical value: the method is suitable for all types of cars, does not require the use of high-speed roller stands or special equipment other than a jack and a phone with a video camera