## 2 Construction Machinery Intelligent Lubrication System Performance Evaluation System
### Influence Factors of Intelligent Lubrication System of Construction Machinery
#### 2.1.4 Lubricant Quality  
(1) The viscosity-temperature curve of the lubricant reflects its fluidity and oxidation resistance, which is of guiding significance in determining the optimum oil temperature and replacement interval [35]. (2) The anti-wear performance of lubricants is closely related to their chemical composition, which is mainly reflected in the extreme pressure additives. (3) The cleaning and dispersing performance of lubricating oil is directly related to the generation of harmful substances such as carbon and varnish produced during fuel combustion, which in turn affects the reliability and life of machinery. (4) During the operation of construction machinery, the viscosity, antioxidant properties, and cleaning and dispersing properties of lubricating oil will be affected by the operating conditions and the external environment and reduced; thus, regular replacement of lubricating oil is essential for the normal operation of the intelligent lubrication system of construction machinery [36].  
Construction of Intelligent Lubrication System Performance Evaluation System for Construction Machinery  
The working environment of construction machinery is dusty and harsh [37], meaning that the performance of construction machinery intelligent lubrication system will be affected by the working conditions. In order to guide the construction machinery intelligent lubrication system to achieve the expected lubrication effect, the construction machinery intelligent lubrication system is required to be able to automatically adjust the lubrication cycle, lubrication volume, and other parameters; this ensures that the equipment is always in the best lubrication state and reduces equipment wear and tear, so as to prolong the service life of the equipment [38]. In addition, the intelligent lubrication system also needs to have a certain degree of predictive analysis capability to ensure that it can analyze historical data and machine operating conditions, predict possible failures in advance, and take timely measures for maintenance to avoid equipment damage or failure.  
Evaluation indexes are the basis for establishing the evaluation system, and also the most basic constituent elements [39]. In order to build an efficient performance evaluation index system, on the basis of reference to the relevant literature, according to the performance requirements of the intelligent lubrication system of construction machinery and the influencing factors and combined with the attributes and characteristics of the construction machinery itself, through the screening and optimization of the evaluation indexes, the performance evaluation system is finally divided into three layers, namely, the target layer, the intermediate layer, and the factor layer, as shown in Table 1. Combining the influencing factors of the intelligent lubrication system of construction machinery, the four indicators of the intermediate layer are first-level indicators, including lubrication effect, fault maintenance, economic cost, energy saving, and consumption reduction. The fifteen factors in the factor layer are secondary indicators [40].