Study On The Precise And Fractionized Flywheel System Of Automobile Chassis Dynamometer

With the incessant progress of the science and technology, the automobile industry of country developes rapidly. In our country the quantity of automobile increasing quickly, the types of automobiles being multiple, and the structure and application of them being more and more complex. Traditional method of detection can't meet the demand in automobile field. These requires when we vigorously develop auto industry, we should also accelerate the development of automobile detection profession, so that we can detect automobile's technical condition quickly and accurately with devanced detection devices, which is the important means to guarantee that antomobiles have good performance.Autobobile dynamic performance is the most fundamental and important in various performance, accelerating time is an important index of measuring the automobile dynamic performance. The comprehensive mark of automobile chassis technology status is sliding distance. Good automobile chassis technology status mean that the fore wheel position is correct, there is the normal clearance between the brake friction plate and brake drum(disc), tire pressure is normal, the slip grinding surfaces of each relative movement parts are smooth and have normal clearance, else have enough lubricating oil. So sliding distance is longer of the car because of the smaller driving resistance. There is two methods for automobile performance test. One is the outdoor road test, the other is the indoor frame test. The weather, condition of the road and the driving skills have great influence on the road test. However these factors have little influence on the indoor frame test. So the indoor frame test goes popular in the automobile test. Antomobile chassis dynamometer plays an important role in the automobile detection and diagnosis.Chassis dynamometer, also known as drum test bed is a door roller test equipment. It can simulate the actual resistance of a driving car, measure the use performance of automobile, detect the technical condition of automobile and diagnose the fault of automobile. Chassis dynamometer can be used for vehicle scientific experiments, also be used for maintenance. The rapid development in the automotive industry today, chassis dynamometer as a vehicle diagnostic equipment generally used for the automobile manufacturing industry, the green emission testing, judging the regenerating the abandoned car of in the country of the relatively developed automobile industry. Since the electric simulation inertia system is not yet ripe, and the high price, it can not widly used in automobile performance testing lines. Most chassis dynamometer still with the flywheel system. Chassis dynamometer flywheel system is using its moment of inertia to achieve accelerated simulation of the vehicle acceleration test; storing the power of a driving car to realize the test of sliding distance and judging the resistance of transmission and driving system; Simulating the inertial quality, and achieving vehicle emission test of multiple loading conditions.This paper tries to develop a precise and fractionized flywheel system of chassis dynamometer. It involves the following aspects:1,Through analysis of the domest and foreign chassis dynamometer and research of the revelant units for the chassis dynamometer, bringing up a scientific flywheel classification standard and studying on the principle of vehicle acceleration and sliding performances test on the outdoor road and the chassis dynamometer2,According to the range of the vehicle simulation quality, the series of the flywheel is nine. Fractionized 512 series in the range of 500～10500㎏ for vehicle simulation quality, so the minimal simulation quality is 20kg. The technology improves the accuracy of the simulation. Scientificly computing the moment of inertia of the flywheel, rationally designing the structure of flywheel and measuring the the moment of inertia of the flywheel, so that the flywheel precision is within the margin of error. In order to prevent the flywheels which are not selected influencing the result, design the braking system that the traditional chassis dynamometer flywheel group does not have. Calculating and checking the shaft as a key part. Choosing Jaw-electromagnetic clutch to control the flywheel.and designing unitary support device to make the installation and maintenance easy. Do the dynamic balancing test of the flywheel in each grade to reduce the vibration when the rotation.3,Since the test involved in a important parameter-the driven wheel moment of inertia, should build a database on all vehicles driven radius and rotational inertia. This paper describes the principle and method of this parameter in detail, and measure the driven wheel moment of inertia of several models. Reasonably selecting the speed sensors, I/O card, A/D board and the relay. Analysing the the automatic matching method of flywheel and the processes of vehicle acceleration and sliding performance test.4,After calibrating the speed sensor and force sensor of automobile chassis dynamometer based on the precise and fractionized flywheel system, respectively for Toyota Camry and JinBei van, do vehicle acceleration test and sliding performance test on the road, automobile chassis dynamometer based on the precise and fractionized flywheel system and on the existing XXX-10E type chassis dynamometer. Through the comparison of the three results, the result automobile chassis dynamometer based on the precise is closer the result on the road the result than on the existing XXX-10E type chassis dynamometer. The tests prove the veracity of the the precise and fractionized flywheel system. Then analysing the errors about this system.The automobile chassis dynamoneter itself is very complicated. This thesis can't describe every aspects in detail. And it's hard to avoid some mistakes and disadvantages. The testing system needs to been further researched and improved.