| With the rapid development of the economic in China,the improvement of road conditions,the average running speed of vehicle is continuously improving,more and more automobile manufacturing departments and maintenance departments industry attach importance to test and adjust wheel alignment parameters.The vehicle stability and traffic safety in the operation, the wear of tire and abnormal increase in fuel consumption are relate to the vehicle wheel alignment parameters,Automobile wheel alignment parameters are a group of wheels installed static geometry angle and size numerical value. Include the caster angle, Kingpin inclination, and the wheel camber angle, toe-in angle.Therefore, In order to maintain good technical condition, Four-wheel aligner is used to test wheel alignment parameters of the vehicle. Four-wheel aligner is a special equipment to test the automotive wheel alignment parameters. At present, the equipment has been widely used in automobile manufacturing departments, maintenance departments and management industry, there are various four-wheel aligners. They have different structures and metrical methods. But if the Four-wheel aligner is inaccurate and theirs own technical indicators are below grade, Four-wheel aligner fails to test the safety performance of motor vehicles. It is regrettable that the problems exist widely in our country, which brings more dangerous factors and hidden troubles. The incidents are bound to increase. Therefore, we trace the measures to the national standards regularly to make sure the right status of the test equipments so that we can trust the test results. First of all, we guarantee Four-wheel aligner for the good technical condition, the results which the vehicles are tested are ensured to be accurate and reliable. So it makes great sense to calibrate the automobile Four-wheel aligner regularly according to correlative calibrating standards. However, at present, none of the portable devices can test the parameters of all kinds of different models Four-wheel aligner accurately and timely. In other words, the area which Four-wheel aligner is tested is a blank in China.In the light of the above analysis, I study the traditional theory of wheel alignment parameters in-depth, according to the requirements of domestic car manufacturing industry and vehicle maintenance industry, I manufacture a new type Four-wheel aligner equipment. Compared to the equipment and the previous testing equipment, it has the following advantages: small size, light weight, convenient debugging, measuring rapid, accurate detection, detection of high precision.In this paper, I discuss the following several aspects:1. Detecting principle and method of Four-wheel aligner calibrating apparatusI expatiate on the several parameters'conception of Four-wheel aligner, the vehicle will be failure when the Four-wheel aligner parameters don't meet the Standard values, and how to adjust the parameters of Four-wheel aligner after automobile traffic generated. I study the measurement principle of the parameters, the several parameters of the measurement are divided into two categories: the direct measurement parameter and indirect measurement parameter. Direct measurement parameter includes the toe-in and camber. The two parameters do not have the theory error in the measurement process; indirect measurement includes caster angle, kingpin inclination.The parameters of direct measurement are not discussed too much, the two parameters of indirect measurement are analyzed by a mathematical model, the perpendicular is longitudinal plane of the wheel center to king pin axial cord, the perpendicular around the king pin axial cord of the vertical axis of rotation to come into being a plane, using the geometric relationships of the plane and wheel alignment angle, I deduce the geometric relationships equation of caster angle and kingpin inclination, and discuss the measurement method of two parameters too.2. The research on the structure and detection accuracy of Four-wheel aligner calibrating apparatusI introduce the technical indicators of Four-wheel aligner, and analyze the problem to the existing Four-wheel aligners.According to the relations among the wheels, sensors and the kingpin in testing course. I have developed a new Four-wheel aligner calibrating apparatus, it can detect the location parameters of Four-wheel aligner, the location parameters include wheel toe-in, camber, caster angle, kingpin inclination.The developed Four-wheel aligner calibrating apparatus has lots of innovations: According to different sensors have different axis sensors, I design different sensors jacket to different axis sensors; Using of the two mutually perpendicular Guide,I can adjust the caster angle and kingpin inclination independently. When I adjust the king pin angle, the mutual influence is avoided between the caster angle and kingpin inclination.The structure and principle of the Four-wheel aligner calibrating apparatus are discussed. I analyze the important components in the Four-wheel aligner calibrating apparatus by the finite element, and find out the stress concentration point, and affect the accuracy of the devices are analyzed.3. Error analysis of the sensor installation and the research on testing circuitIn this part, I discuss the installation of the encoder, and choose the optimal scheme by the two scheme error analysis. Encoder replaces the Dial Turntable of the past Four-wheel aligner calibrating apparatus, thereby the weight of the test device is greatly reduced, and it can get more precise data. I study the function of the Four-wheel aligner calibrating apparatus system in-depth, the LPC2132 is the core processor to control unit, I design the circuit of the signal acquisition and the data display in the device, and the necessary procedures are done.4. The research on precise feeding of the device and analysis of test dataI discuss the significance of precise positioning devices, and I design the test bed equipment according to the study need. After multiple debugging and the test data is obtained. The results of data processing analysis prove that to achieve precise positioning is feasible in the Four-wheel aligner calibrating apparatus. |
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