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汽车四轮定位与倾角传感器

汽车在出厂时，四个轮的定位角度都是根据设计要求预先设定好的。这些定位角度共同用来保证车辆驾驶的舒适性和安全性。但是，车辆在行驶一段时间后，这些定位角度会由于道路坑洼不平造成的剧烈的颠簸（特别是高速行驶时突然遇到不平路面）、底盘零件磨损、更换底盘零件、更换轮胎等原因而产生变化。一旦定位角度由于任何一种原因产生变化，就可能产生诸如轮胎异常磨损、车辆跑偏、安全性下降、油耗增加、零件磨损加快、方向盘发沉、发抖，车辆发飘等不适症状。所以汽车在行驶一定时间或一定距离后都要进行四轮定位维修保养服务，其目的就是通过定位角度测量诊断车轮的定位角度偏差并予以矫正。要实现角度的准确测量，四轮定位仪中测量角度的倾角传感器将起到关键性作用。

正因为倾角传感器的关键性作用，在设计和生产四轮定位仪时倾角传感器的选择是非常重要的，它是决定设备准确测量、产品质量和产品档次等重要指标的基础。+

选择倾角传感器的常要考虑的参数

选择倾角传感器的首要参数是精度，当今在用的车型，倾角的调整偏差值一般在 5' 左右，如：上海大众 PASSAT B5 前轮的外倾角值为 -0 ° 35' 至 ± 0 ° 25' ，所以倾角传感器的测量精度要求在0.1度以内，而且这一精度要在较宽的温度范围内都能满足。因为在中国，进行四轮定位的维修厂通常都在室外或敞开的环境，在北方零下二十度时也要正常工作，这就要求倾角传感器的温度稳定性要好。

选择倾角传感器的第二个考虑参数是测量量程，也就是传感器的测量范围。在四轮定位中大部分车型的角度都在±10°以内，也有个别车辆的个别角度会在±15°左右，所以四轮定位用的倾角传感器最佳测量量程是±15°。  

第三个需要考虑的参数是产品的频率响应。在测量的过程中经常要对设备进行移动或调整，若传感器的响应频率响应宽，则在测量时读数很难稳定，所以要求传感器低频响应好。

第四个需要考虑的参数是产品的抗振能力。倾角传感器固定在四轮定位仪安装底板上，再通过夹具安装在汽车的车轮上，在安装、应用或调整车轮角度时，常会受到一定的冲击，所以要求倾角传感器的抗振性能要好。

第五点需要考虑的参数是长期稳定性。长期稳定性好的传感器才是整个设备能长期稳定工作的保障。以上五点是在为四轮定位仪选择倾角传感器时主要重点考虑的参数，它们直接决定了四轮定位仪的品质。

Four Wheel Positioning and Inclination Sensor for Automobile

When the car leaves the factory, the positioning angles of the four wheels are pre-set according to the design requirements. These positioning angles are used to ensure the comfort and safety of vehicle driving. However, after a period of time, these positioning angles will be changed due to the severe bumps caused by road bumps (especially the uneven road surface when driving at high speed), chassis parts wear, chassis parts replacement, tire replacement and other reasons. Once the orientation angle changes for any reason, it may produce discomfort symptoms such as abnormal tire wear, vehicle deviation, safety decline, fuel consumption increase, accelerated wear of parts, steering wheel sinking, shivering, vehicle drifting and so on. Therefore, after a certain time or a certain distance, automobiles have to carry out four-wheel alignment maintenance service. Its purpose is to diagnose and correct the wheel alignment deviation by measuring the alignment angle. In order to achieve accurate angle measurement, the inclination sensor of measuring angle in four-wheel positioner will play a key role.

Because of the key role of the inclination sensor, the selection of the inclination sensor is very important in the design and production of four-wheel positioner. It is the basis of determining the accurate measurement of equipment, product quality and product grade. +

Parameters to be Considered in Choosing Inclination Sensor

The primary parameter of selecting inclination sensor is accuracy. The adjustment deviation of inclination angle is generally about 5'in the current vehicle models. For example, the inclination angle of the front wheel of Shanghai Volkswagen PASSAT B5 is from -0 35' to 0 25'. Therefore, the measurement accuracy of inclination sensor should be within 0.1 degrees, and this accuracy should be satisfied in a wide temperature range. Because in China, maintenance factories that carry out four-wheel positioning usually work outdoors or in an open environment, and they also need to work normally at minus 20 degrees in the north, which requires that the temperature stability of the inclination sensor be good.

The second consideration in choosing the inclination sensor is the measurement range, that is, the measurement range of the sensor. In the four-wheel positioning, the angles of most models are within (+) 10 degrees, and the angles of individual vehicles are about (+) 15 degrees. Therefore, the optimum measuring range of inclination sensor for four-wheel positioning is (+) 15 degrees.

The third parameter to be considered is the frequency response of the product. In the process of measurement, the equipment is often moved or adjusted. If the response frequency of the sensor is wide, the reading is very difficult to be stable, so the sensor is required to have good low-frequency response.

The fourth parameter to be considered is the anti-vibration capability of the product. Tilt sensor is fixed on the bottom plate of four-wheel positioner, and then installed on the wheel of automobile through fixture. When installing, applying or adjusting the wheel angle, it often suffers certain impact, so the anti-vibration performance of the tilt sensor is required to be better.

The fifth parameter to be considered is long-term stability. The sensor with good long-term stability is the guarantee for the long-term stable operation of the whole equipment. The above five points are the main parameters to be considered when choosing inclination sensor for four-wheel positioner. They directly determine the quality of four-wheel positioner.