Tractor handlebar vibration vibration source and vibration characteristics

 

Key words: tractor, hand vibration, diesel kinetics modal analysis, vibration mode; Zhen Jue; inherent rather rate, vibration characteristics

 

The circle words 5219. 60 a; 0527

 

Currently in China, tractor farm tractor is one of the main models. As the handle of a tractor beam suspension Gan structure, and single-cylinder diesel engines, so severe vibration at the handles when working, the vibration level exceeds the human body can t bear range, may cause the arm blood vessels, nerves , bones and joints and other tissues of serious injury. On the other hand, the vibration will affect the normal operation of tractor, causing structural fatigue damage or off the file. For these reasons, tractor handlebar vibration caused many domestic governance of researchers' attention. China has begun to develop a standard for tractor handlebar vibration.

 

Currently our concern is how to reduce the magnitude of vibration at the handles tractor.

 

Tractor vibration of the handle structure and the tractor driver system composed of a large body surface and the two main excitation engine response, the size of not only the characteristics of these two kinds of excitation, but also on the entire large-scale systems dynamic characteristics. Many scholars have studied the domestic tractor dynamic characteristics of the structure itself, but the actual work involved in the driver not only change the original structure of the mass distribution, but also changed the handlebar support conditions, it must be driving the tractor and members as a whole to study.

 

I use experimental modal analysis technique and the driver of the tractor structure composed of a large body dynamics of the system, get a tractor driver system natural frequency, vibration mode and other modal parameters, then theoretically more systematic analysis of the road excitation and excitation characteristics of each engine and quantitatively determined by testing these two kinds of opponents of the vibration excitation effect, results show that the excitation is caused by engine vibration at the handles of the main reasons. This provides vibration at the handles provide a basis for governance.

 

A tractor a pilot system dynamic characteristics

 

In order to study the tractor driver during normal operation of the dynamic characteristics, using experimental modal analysis method and the driver of the tractor structure composed of a large body dynamics of the system.

 

Tests on the tractor placed on a rigid stand on the vibration table with a big thrust imposed 1 0 N random excitation force structure and the tractor driver's test t of 25 points on the body's response. Subjects the driver is tall 1.70 m, weight 60 kg in healthy young men. Tests require drivers to work as usual, like holding a hand. For test methods and test detailed in the literature [4].

 

Curve fitting method using the measured frequency response function quite parameter identification, the system has been tested in the top 10 natural frequencies and the corresponding mode shapes. In which Figure 1 is closely related with the hand vibration 7th and 8th-order natural frequency and 3.05 Hz) corresponding to the vibration type. This two vibration mode indicates the amplitude at hand and manpower are great.

 

It is worth noting that this second-order natural frequency of the rated speed of the engine 2 O0 r / m in the vicinity, that is when the engine work a tractor driver will cause the resonance system. This is caused by tractor vibration handle the underlying reasons.

 

2 Analysis of vibrational source handle

 

A road excitation opponents to the effects of vibration

 

Parameters of the tire under the same conditions, road surface facing the tire force and uneven geometry and physical properties of the ground, but also on the running speed of the wheel [s1.

 

Driving speed is high, the projecting portion of the tire on the road contact time is short, the impact force, the vibration caused by the violent, so the high speed on the highway tractor vibration handle much larger than the field operations. However, due to tractor tire pressure is low, uneven ground encountered at large deformation of the tire, the road and the tire contact time longer, and tire rubber layer is very thick, have a greater impact on the damping effect, so the impact caused The rapid attenuation of high frequency components, such as surface irregularities caused by the vibration of high frequency components is small.

 

3 handlebar vibration measured results

 

These theoretically analyzed two kinds of incentives characteristics. As the road situation is complex, and the tire on the road is difficult to set an impact force t analysis of each of the vibration excitation opponents quantitative relationship can be tested by experiment.

 

Test, respectively, the load and the vehicle speed measured under the same conditions, and by other normal driving tractor vehicle drag rope handle vibration signal. Through the analysis of these two sets of data can be obtained when the actual work tractor road excitation and engine excitation opponents to the quantitative relationship between the effects of vibration.

 

Test for the workers and peasants, a 12-type tractor tractor, its engine is 5195 diesel engine. Test for the 1.st quality tow tractor trailer, the car is equipped with I t sand. Tractor driving in general tarmac. Test apparatus shown in Figure 4. Handlebar vibration signal slightly. K 4 3 21 type three accelerometers measure the accelerometer with a special jig handlebar clamp tractor driver operates in the vicinity (in order to not affect the driver's operation is limited). Vibration signals measured by the scoop Force K 2 6 3 5 type charge amplifier, the use of MR-3 OC recorded tape drive, then play in the laboratory and with slightly K 2 0 3 4 type dynamic signal analyzer, to give handlebar vibration acceleration in three directions from the power spectrum and the rms value of the total acceleration. 3 handlebar vibration direction. And the island by hand vibration direction defined by the international standard drawing OK.