Study On Braking Performance Of Passenger Cars Equipped With Permanent Magnet Retarder

Permanent magnet retarder is a kind of new auxiliary braking device with excellent performance and high value-added, which has the advantages of light weight, energy saving and environmental protection, and no maintenance. It can effectively share the braking load of service brakes, reduce its hot recession property and improve its life, and then improve the driving safety of vehicles.In this paper, the braking performance and stability of passenger cars equipped with permanent magnet retarder were analyzed by using the method of theoretical analysis and simulation study, and the simulation data were compared with the experimental data. The structure, braking theory, braking torque calculation, the installation and control ways of permanent magnet retarders were introduced. The braking torque was not the bigger the better and it should be guaranteed that ground braking force acted on rear wheels was not greater than the adhesion when passenger car match permanent magnet retarder; the initial braking force that the retarder forced on rear wheels should not be too great, it should be ensured that the β-curve and I-curve have intersection points; the braking force distribution coefficient should be increased appropriately to weaken the trend of rear wheels locked firstly, and shorten the time lag.The combined brake system of passenger car was established. The braking performance of passenger car equipped with permanent magnet retarder was analyzed from four aspects, which were continuous braking on the flat road, steady speed under the continuous long slope, emergency braking on the flat road and emergency braking under the long slope. On the flat asphalt pavement, the braking distance was respectively shortened by46.5%,55.7%,52.3%with permanent magnet retarder; shortened by31%,55.8%,40.2%with exhaust braking; and shortened by56%,71.8%,74.1%with combined braking in high speed range(100-50km/h), medium speed range(80-40km/h) and low speed range(60-30km/h), and the braking efficiency significantly was improved. The maximum error was only2.3km/h by comparing the the simulation velocity value and the experimental velocity data. To some extent, the simulation model was verified.