The braking performance of a car is an important performance to ensure the safety of the people in the car and the safety of the vehicle. After the manufacturer designs and produces a car, it will conduct a braking performance test on it. As a car repairer, when encountering a brake failure , Braking performance testing is also required after maintenance. What are the braking performance testing methods for cars? The following editor of Naiou has compiled the test methods and evaluation indexes of automobile braking performance for your reference.
One 、 Evaluation index of automobile braking performance
There are three main indicators for evaluating automobile braking performance:
1. Braking efficiency: the braking distance and braking deceleration. It refers to the braking distance between the car at a certain initial speed and the deceleration of the car during braking on a good road. The braking performance is the best Basic evaluation indicators.
2. The constancy of braking efficiency: the degree to which the car's braking efficiency is maintained when driving at high speed or continuously braking down a long slope is called the thermal decay resistance. In addition, when a car is wading through water, water enters the brakes, and the reduction in braking efficiency in a short period of time is called water recession. The car should quickly restore the original braking performance in a short time.
3. The directional stability of the car during braking: that is, the performance that the car does not deviate, slip and lose its steering ability during braking.
1, bench test
According to the movement condition of the vehicle being inspected relative to the ground during the inspection, the braking performance test test is divided into static test method and dynamic test method. The static test method uses a roller reaction brake test bench, and the dynamic test method uses a flat brake test. station.
(1) Static detection method
At present, the automobile inspection station uses the counter-force roller brake inspection bench as a universal instrument for the inspection of automobile braking performance. Its advantages are: low vehicle speed, high detection safety factor; convenient streamlining operation, rapid detection economy; repeatability Better, it can quantitatively measure the whole process of braking growth, which is conducive to judging the fault location and formulating the correction plan for unqualified cars; in addition to the equipment and workshops, it is less restricted by external conditions and is convenient for testing the layout of the site. But it has the following shortcomings:
A. The detection state is inconsistent with the actual braking state of the car.
B. It is difficult to scientifically detect automobile braking stability.
C. It is difficult to accurately detect the braking performance of a car equipped with ABS.
(2) Dynamic detection method
The flat-plate brake inspection platform used by the dynamic method has simple structure, small daily maintenance workload, strong working reliability, and high detection efficiency. Now it is more and more favored by inspection stations. However, the pin-plate brake inspection platform also has its shortcomings:
A. The faster the speed, the greater the kinetic energy, so the braking force measured on the flat brake platform at different vehicle speeds is different, resulting in poor repeatability.
B. The flat brake test bench measures the braking force of the car, while the drum reaction brake test bench measures the braking force of the wheels. None of the existing methods for measuring the braking performance of a vehicle can be said to be more accurate, but only which method can more accurately reflect the braking performance of the vehicle under test.
C. The flat brake test bench cannot test the wheel blocking force.
2. Road test
It is stipulated in the relevant standards that if there are objections to the results of the braking performance of the bench test, the road test re-inspection shall be carried out in the no-load state according to the regulations. If there are objections to the re-inspection results of the no-load state, the full-load road test re-inspection results quasi. Therefore, road test inspection is the final judgment method of automobile braking force performance inspection. The braking performance road test can truly reflect the dynamic braking performance of the vehicle during actual driving, such as the impact of axle load transfer, and it can also comprehensively reflect the impact of the structural performance of other vehicle systems on the vehicle’s braking performance, such as steering mechanism and suspension. The impact of the structure of the frame system on the stability of the braking direction, and does not require large-scale equipment and workshops, but the braking performance road test inspection has the following shortcomings:
A. It is not conducive to streamlining operations and low efficiency: With the rapid increase in the number of cars, the current inspection station has to bear hundreds of inspection tasks every day, and it is not only for testing the braking performance. Road test inspection requires a large site that is isolated from other areas and meets the requirements. If it is not streamlined operation, it is impossible to complete such a task without high efficiency.
B. Only an overall analysis: the brake road test test takes the actual driving and the entire car as the research object, and can only quantitatively evaluate the braking performance of the whole vehicle, but for the braking condition of each wheel and the distribution of braking force, It is impossible to detect and accurately determine the fault location, which is not conducive to formulating a correction plan for unqualified cars, and it is not conducive to diagnosing the specific location of the fault.
C. There is a certain degree of danger: the brake road test test is a dynamic high-speed test that is closer to the actual driving, especially the full-load road test. If the detected vehicle has a brake failure, the braking distance may be too long and the direction may be too long. Poor stability and other issues, so there are certain security risks.
Regarding the detection methods of automobile braking performance, the above are the test methods and evaluation indicators compiled by Naiou editor for everyone. I hope it can be helpful to everyone. Correctly judging whether the braking performance of a car is qualified is the purpose of testing the car. Only by choosing the correct test method and braking test system can the misjudgment be reduced in the test. Luoyang Naiou Electric Co., Ltd., as a high-tech enterprise focusing on the research, design and manufacture of vehicle performance test systems, has designed a variety of performance test systems and supporting sensors for different vehicle performance inspections, and all of them fully meet the vehicle test standards If required, you can leave a message on our website or call the customer service phone for detailed consultation.