Steady Heat Characteristics Analysis Of Wet Drive Axle On Huge Wheel Loaders

The wheel loader is a kind of scraping and transporting machine, which is widely used in urban construction and many projects, such as highway, railway, port, wharf, cool, mine, water conservancy and national defense. To scoop up the incompact material and take short distance transport is the major function of it. For the advantage of rapid working velocity, high efficiency, excellent maneuverability and handiness, it is regarded as the one of major machineries for earth rock construction in the projects. Furthermore, the manufacturing capacity and research of huge wheel loader represents manufacturing level of a country to certain extent, it also stands for a country's whole manufacturing level.The back driving axle is one of the most important components in a loader it outputs momentum for other drive mechanism. The back driving axle of ZL80 wheel loader is composed of pendulum axle and the wheel side brake is composed of wet planetary clutch. Besides used as driving axle, the pendulum axle also keeps the bodywork balance by shaking the axle, preventing the danger of barycenter's offset, when it runs on the incline or one of the tires sticks up .For as much as good heat dispersion, reducing the working temperature, improving the service life, the wet clutch is widely used in engineering vehicles.Back driving axle is the integral part of the driving system of the loader's underpan, being at the end of the driving system, in poor working operational environment, with gearbox structure. It may result in power loss, at one time, the accessory will cause stirred oil loss in operation, because the fraction occurs when the major transmission, side wheel transmission, axletree and detent are in use, the above thermal loss not only carries weight on the lubricate and cooling of the system, but also it effects the working strength of the constructional element. The damage process of each driving mechanism, due to heighten of the thermal operating condition usually begins ,when the lubrication of engine oil working on the friction surface metamorphoses (oil decomposing, resinification).The aftermath from exorbitant heat calorific intensity arose the damage of the loader. It requires engineers to calculate the heat quantity of each frictional component accuratly, to adopt effective forced lubrication system and oil cooling system with radiator, to ensure the normal thermal working condition and solve the problem successfully.In this paper, the 3D simplified model of back driving axle (ZL80 wheeled loader) is firstly constituted. Eight operating conditions are selected. According to the dynamic and kinetic theory, I explain how to solve for each driving component's thermal loss, from wheel to major transmission according to the state of the wheel, and compute the total heat quantity of the back driving box in eight typical operation conditions.In the next place, lumped parameter method and thermal network method in heat transfer are adopted to simple the structure of the back driving axle .Because of excessive local detail in the back driving axle box, to improve the efficiency and the reliability of the result. I make some rational reduction even neglect at the parts which have little affect in the analysis, when lumped parameter method is adopted to make gridding on the surface of the box ,the surface is approximately reduced to planar and cylindrical heat transfer geometric model. Setting up the whole steady heat transfer model of the back driving axle box, writing iterative program in MATLAB, I solve for the oil temperature of the back driving axle box at the steady heat balance, and attain the temperature rise status and the heat dissipating capacity of the surface in different conditions. Using the date fitting function of MATLAB,I fit out the time variation curve of oil temperature in the back driving axle box .After analyzing the steady thermal property of the back driving axle box and heat dissipation potential ,I get the factors that affect heat dispersion of the box surface and provide measures to improve the heat dispersion property. Checking the temperature rise of wet wheel side brake, verificating the rationality of the design, comparing with traditional shoe brake, I sum up advantages of this kind of wet brake.Finally, 2D solid model of back driving axle is set up in ANSYS, and is partitioned with four-node quadrilateral elements by PLANE55 .The whole temperature field of back driving axle is solved by thermal analysis module of ANSYS. The distributing nephogram of whole temperature field is analyzed and also the highest temperature point and local high temperature part are found. More attention should be paid to these heat source parts, and heat dispersion conditions should be improved in the local heat up parts, to enhance the working strength and keep off longtime overheating damage.