Vibration reduction and maintenance methods for construction machinery engines

The engine is the main source of vibration in construction machinery. Some effective methods should be adopted to reduce vibration.

I. Vibration Source Control

Vibration source control runs through the entire process from design, manufacturing to use, and is reflected in aspects such as improving the engine's balance performance, dynamic performance, and the processing and assembly accuracy of components. The forms of vibration generated by an engine during operation are diverse. The main reasons include: the periodic movement of the engine's center of gravity, the inertial force acting up and down along the cylinder by the reciprocating parts, the centrifugal inertial force of all rotating parts, and the alternating action of gas pressure causing changes in the crankshaft's rotational period, etc. These unbalanced forces and moments can usually be adjusted by changing the design parameters of the engine results to regulate the natural frequency of the system and avoid structural resonance, thereby improving the resonance characteristics of the system. For instance, the mode shapes of the natural frequency of the engine can be studied through modal analysis and finite element calculation of the engine block. Weakening the vibration source and avoiding resonance should first be considered in the design stage. The concept of systems engineering should be integrated throughout the overall design, and modern design methods such as finite source design, reliability design, robust design, optimization design, computer-aided design, as well as intelligent system and expert system design should be fully applied.

Ii. Isolation of Vibration

1. Rubber vibration isolation

Traditional engines use elastic supports to reduce vibration. The vibration isolation device has a simple structure, low cost and reliable performance. Rubber supports are generally installed on the vehicle frame and are classified into compression type, shear type and compression-shear composite type, etc. according to the force conditions. The compression type has a simple structure, is easy to manufacture, and is widely used. However, due to its high natural frequency, it is generally limited to use in the vertical direction. The shear type has a relatively low natural frequency but not high strength. The compression-shear composite type integrates the advantages of the previous two structures and can meet the requirements of durability and reliability. This is currently the most widely adopted type both at home and abroad. In order to ensure that the vibration isolation rubber support system has better vibration reduction performance, the parameter table requires the spring constant in the same direction, which can also reduce the several dimensions. String 8

2. Spiral steel wire rope vibration isolation

As a vibration damping component, steel wire rope features variable parameter performance with high damping at low frequencies and low stiffness at high frequencies, thus effectively reducing the vibration of the machine body. Compared with traditional rubber vibration isolation sources, it has the advantages of oil resistance, corrosion resistance, temperature difference resistance, high temperature resistance, aging resistance and small volume. The vibration isolation effect mainly depends on its nonlinear hysteresis characteristics.

3. Hydraulic vibration isolation

The hydraulic support system is a structure that integrates traditional rubber supports and hydraulic damping. It can provide significant damping in the low-frequency range, rapidly reducing the large vibration of the engine. At medium and high frequencies, it has low dynamic stiffness and can effectively reduce the vibration and noise in the driver's cabin.

Iii. Control of Vibration in Construction Machinery Engines

In engineering, resonance is sometimes inevitable. Therefore, it is common to increase the system damping or use dynamic vibration absorbers to reduce the vibration response. The dynamic vibration absorber belongs to the frequency band control and uses viscoelastic damping materials, which have a very high energy loss. When the vibration is transmitted to the damping material, tensile, bending, shearing and other deformations occur inside the material, thereby consuming a large amount of vibration energy and causing vibration attenuation. The main advantage of using damping technology for vibration reduction is that it does not require changes to the original structure, no need to add auxiliary equipment, no need for external energy, and occupies less effective space. It is a very promising measure for vibration reduction and noise reduction. The new product 955A wheel loader produced by Zhengzhou "Yutong Heavy Industry" is the first to adopt this dynamic vibration absorber in the selection of shock absorbers, achieving an ideal vibration reduction and noise reduction effect through new technology.