Establish oriented operating terminals wheel loader duty cycle

Abstract: The wheel loader simulation analysis needs oriented operating terminals duty cycle to set the virtual reality environment, and the energy-saving potential research of hybrid or other new type wheel loader should also be based on the duty cycle. But there is no wheel loader duty cycle to date, which obstructs the energy-saving mechanism and simulation research about wheel loader. An oriented operating terminals duty cycle was established based on wheel loader working test data, and the duty cycle described the basic energy consumption rules of wheel loader operating terminals. A CLG862Ⅲ wheel loader was used for the working test, with the rate load of 6 ton. The testing data was collected at all the operating terminals, the wheel loader worked with two typical materials in the working test, one material was soft earth and the other was raw earth. In order to avoid the difference caused by operators, two operators were engaged in operating the wheel loader, and every test was required to work more than 60 cycles continuously. Ninety percent of the test data was used for relevant features extracting and duty cycle establishment. Statistical analysis was used to extract relevant features from working testing data, the relevant features included 4 series vehicle velocity series, running resistance series, machine weight series and hydraulic resistance torque series. The relevant features were expressed on 4 separate coordinates at the same time sequence to establish wheel loader duty cycle. The duty cycle was established according to the following process: 1) the time sequence was divided into 5 phases on the vehicle velocity coordinate, including: run to pile, input pile, loading backward, run to truck and unload return phase; 2) the 4 transport phases were expressed as vehicle velocity polyline trapeziums by the relevant features, including: the highest velocity, the second highest velocity, maximum acceleration, maximum deceleration and phase continuance time phase continuance time; 3) the input pile phase was combined with running into pile phase as one unit; 4) a smooth vehicle velocity curve was generated by the means of 4 order fitting; 5) the vehicle velocity curve was amended with the constraint condition of wheel loader operated in fix location, that means wheel loader forward driving distance equaled to backward driving distance when it was working; 6) the input resistance relevant features were expressed on the running resistance coordinate, and its time sequence was corresponding with input pile phase; 7) the loading relevant features were expressed on the machine weight coordinate, with load phase started at the beginning of input pile phase and ended at the beginning of unload return phase; 8) 3 steering phases were expressed on the hydraulic resistance torque coordinate, the steering phases were located in the middle of run to pile, loading backward and unload return phase respectively; 9) tilt bucket phase relevant features were expressed on the hydraulic resistance torque coordinate, it was 0.5 s behind input pile phase beginning; 10) lift & steering phase relevant features were expressed on the hydraulic resistance torque coordinate, and it started at the beginning of run to truck phase. The remaining ten percent test data was used to validate the duty cycle. The results showed that duty cycle could accurately describe wheel loader operating terminals power requirement. The wheel loader duty cycle could provide power requirement data for the parameter matching of hybrid driving wheel loader and new types of wheel loader power-train. It could also be used for computer simulation including dynamic analysis. At the same time, it could offer a detailed and unified experimental standard for traditional wheel loader performance testing.