摘要
针对目前非公路自卸车油气悬架系统温度变化的研究中未考虑缸筒和活塞杆热容的问题,该文引入集中参数热模型法对非公路自卸车油气悬架系统温度变化进行研究。运用热学理论、气体状态方程,建立包含缸筒、活塞杆热容的非公路自卸车油气悬架系统的集中参数热力学模型。通过求解热力学模型方程组,分析非公路自卸车油气悬架系统中油液温度的变化趋势,并将结果与试验结果进行了对比。对比的结果表明集中参数热力学模型能较准确的描述非公路自卸车油气悬架的热力学状态,而且考虑缸筒、活塞杆热容量会增加系统的温度变化的迟滞效应。该研究将有利于精确描述非公路自卸车油气悬架的动力学特性,同时也为其他工程或农用车辆上油气悬架热力学研究提供了有益的参考。
Hydro-pneumatic suspension is an important part of off-highway dump trucks. It represents a compromise between ride comfort and handling stability via its nonlinear character. Off-highway dump trucks generally use the single air chamber hydro-pneumatic suspension system to achieve a vehicle’s reliability and economy. But the effect of temperature changes on the output force characteristics of the hydro-pneumatic suspension, which results in ride comfort and ride height, is one of the urgent problems in its design and use. This paper presents a thermodynamic study of the hydro-pneumatic suspension using a lumped parameter model. It is known that this method is used to solve thermal problems by analyzing thermal networks by analogy to electrical circuits. This method has been used for a long time to calculate the temperature rises in electrical and spacecraft systems. Different from other studies, the cylinder and the piston rod thermal capacitance are taken into consideration in this study. During the study, the suspension system is divided into a number of lumped components. Each component has a thermal storage and interconnections to neighbor components through a linear mesh of thermal resistances. The heat is generated by oil flows through the damping orifices and nitrogen compression. Then, based on the gas state equation and thermodynamic theory, the nonlinear equations of the thermal model are established, which originally contain the heat capacity of the cylinder, the piston, and the oil. The simulation analysis is carried out under the model. The results show that, except for the oil in the bottom of the piston rod, while considering the thermal capacitance of the cylinder and piston, the temperature of the suspension system rises slower than if those capacitances are ignored. A validation experiment is performed to confirm the predicted results. The oil temperature in the initial stage of the experiment decreased first and then increased, which is different from the calculated value’s monotonically upward trend. This may be caused by the fact that the oil from the static to flow requires a certain amount of energy in the initial stage of the experiment, while the external input of energy is shortage. Due to the measurement error, the lack of detail in lumped element division, and some other reasons, there are some differences between the experimental data and calculated values, but the tendencies of the experimental and calculated temperature rise of the suspension system are the similar. The comparison results show that the proposed model can describe the thermodynamic state of the hydro-pneumatic suspension more accurately than previous methods. The thermal capacitance of the cylinder and piston will increase the hysteresis effect of temperature changes.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第10期64-70,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
北京市科技支撑市委
市政府重点项目"交流电机驱动百吨级矿用自卸汽车研制"(Z101103055010004)
关键词
悬架
自卸车
热问题
集中参数热模型法
suspension
trucks
heat problems
thermal model of lumped parameter
