Analysis And Improvement Measures Of Automotive Braking Performance II
Analysis And Improvement Measures Of Automotive Braking Performance II
The Constancy of Automotive Braking Efficiency
Factors affecting the constancy of automotive braking efficiency:
(1) Material of friction pair
This is the main factor affecting braking efficiency;
(2) The structural form of the brake
Generally speaking, self boosting is more effective than non boosting, and leading hooves are better than leading and trailing hooves;
(3) Braking time
Try to avoid prolonged braking;
(4) The thermal capacity and heat dissipation capacity of the brake
The larger the heat capacity and heat dissipation area, the better the braking stability.
Therefore, in car design or modification, various factors should be considered, such as selecting appropriate brake materials and brake forms, and providing as much heat dissipation space as possible for the brake.
3、 Directional stability of automotive braking
The directional stability of a car includes three aspects: brake deviation, rear axle slip, and loss of front axle steering ability. The ability to maintain straight or predetermined curve driving during the general braking process is called the directional stability of a car when braking. In automotive testing, a certain width of test channel is often specified, and vehicles that pass the test are not allowed to have uncontrollable effects that cause them to leave this channel during the test.
(1) Car deviation
There are two reasons for this, one is the unequal braking force between the left and right wheels, and the other is the interference of the suspension guide rod and steering system pull rod movement. The former is caused by manufacturing and adjustment errors, while the latter is caused by design, and the latter always causes deviation to the right.
(2) Rear axle sideslip
The reason is that the rear axle wheels lock up and slip before the front axle during braking, putting the car in an extremely dangerous state. If the braking can be achieved by locking the front wheels first or simultaneously, it can prevent the rear axle from slipping. Some electronic devices nowadays, such as ABS and electronic brake force distribution systems, are devices used to control wheel lock up, which greatly helps to improve the safety of car braking.
(3) Loss of steering ability on the front axle
The reason is that the front wheels lock up first, and then the wheels slide. Even if the steering wheel is turned, the car cannot turn and continues to drive in a straight line. Compared to the situation where the rear wheels lock up first, the car is in a relatively stable state due to the centrifugal force of the body.
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