The durability of the wheel hub bearing

2019 - durability of wheel hub bearing 10 - 25 'test load spectrum should be formulated according to the actual situation of vehicle, and combining the feature of vehicle itself, reasonable and effective load spectrum is simulated durability of wheel hub bearing a key'. 1 load spectrum and a full load spectrum of the durability of the driving parameters should include: all kinds of rotation of the wheel hub bearing; Wheel hub bearing in the condition of all kinds of rotating speed; Test load cycle time. Each cycle load change state of travel time distribution rate; Load of various kinds of driving conditions. Car driving state is determined by driving the road surface characteristics and driving speed. Pavement according to the characteristics of a linear can be divided into straight road and turned to the road; According to the road of the environmental quality can be divided into good poor roads and road surface. For the wheel hub bearing durability test cycle and have no fixed standard; In one load cycle change, each state needs to be given a time value, each time value in one load cycle change the proportion of total time is called the time allocation rate. Due to the particularity of working condition of wheel hub bearing unit used for the analysis to the reasonable design life test load spectrum, so as to accurately predict the comprehensive service life of wheel hub bearing unit. 2 pre-tightening force of the impact on the life in the process of wheel hub bearing unit assembly, appropriate for preloaded bearing unit can not only improve the bearing stiffness, and has resulted in a two column bearing unit increased the number of rolling element bearing, bearing capacity, improve unit so as to prolong the service life of the unit. But too much will increase the bearing pre-tightening force of the bearing load, the unit of life. Under the condition of a simulation test load spectrum, pre-tightening load and nonlinear relation to the wheel hub bearing unit of life. With the increase of pre-tightening load, left and right sides of the wheel hub bearing unit integrated life gradually increase, when reaching a certain value, the left two columns reach maximum wheel hub bearing units of life; Then, with the increase of pre-tightening force, rapid decline in the life of a wheel hub bearing unit. Bridge on the left side of the wheel hub bearing unit life is longer than on the right side of the life of the bearing unit, but with the increase of pre-tightening load, both to close. 3 lateral acceleration effect on the life of the vehicle in the process of driving, in turn, will form a larger lateral acceleration usually at 0. About four times the acceleration of gravity, and time is short. But this time, due to the radius of the tire and the load eccentricity, Wheel force center to the center of the wheel hub bearing axial offset) The influence of would be a big torque load. Under the effect of torque load, the equivalent dynamic load of wheel hub bearing units increase, making the life of the bearing unit to be markedly reduced. With the increase of lateral acceleration rate, wheel hub bearing unit integrated life decreases obviously, as the change of lateral acceleration rate, around the bridge on both sides of the wheel hub bearing units are changed, the life of a whole bridge on the left side of the wheel hub bearing unit life than on the right side of the life of the bearing unit. 4 loading eccentricity affect life in the wheel hub bearing unit design and assembly, wheel hub bearing unit load center and the tire load center there is a eccentricity, the eccentricity of the wheel hub bearing unit carrying an additional moment, make two columns of rolling element bearing unit load distribution changes, which affect the service life of wheel hub bearing unit. Eccentricity is zero, the cab integrated life of left and right sides of the wheel hub bearing units; But when the eccentricity is positive increase, the cab on the right side bearing unit life down, on the left side of the rise; When the eccentricity reduced negative, contrary trend. To zero when the eccentricity is best, but the actual wheel hub bearing units, especially the third generation wheel hub bearing unit, its core axis and the outer ring are connected through the flange structure and other components, the flange when the load the flexible support role brought to bear upon the bearing unit center offset. Therefore, when the actual design at the center of the wheel hub bearing unit load and the load center of the tire design must be offset. 5 tire radius impact on life in the wheel hub bearing unit design, the first thing to determine bearing used in the vehicle type and working conditions. After get the vehicle parameters, the design experiment to simulate the load spectrum of wheel hub bearing unit. Radius of the moment, therefore, the radius of the tire should first determine vehicle parameters. But in the process of actual simulation experiment, for the sake of accelerated test was carried out on the wheel hub bearing unit, generally USES the method of radius increased moment experiment. With the change of the radius of the tire, wheel hub bearing unit rotation speed change subsequently. When the radius of the tire is about a certain size, based on the test load spectrum of left and right sides of the wheel hub bearing unit integrated life, and in other interval is falling fast. Among them, in the small radius when life down, mainly due to the impact of wheel hub unit speed increase on life; And life down, when large radius increase is mainly due to the torque load on the impact of life. （ Source: SQEcollege)