为克服传统齿轮齿条天窗机构存在的诸如响应慢等弊端,设计了一种连栋玻璃温室轨道式气动天窗机构.应用美国温室设计标准,对天窗荷载进行了计算,并通过机构运动学和联立约束法动力学仿真,分析了天窗开度、气缸负载以及推杆受力与气缸活塞行程之间的关系,从而确定气缸行程和活塞直径.分析表明,对于结构尺寸一定的连栋玻璃温室,轨道式气动天窗机构存在最大开启角度,并且开启天窗所需气缸输出推力主要受连杆对横向推杆水平方向分力的影响,而摩擦力的影响很小.选配气缸运行效果仿真表明,与传统齿轮齿条机构相比,气动天窗机构响应速度快、安装方便,有利于提高天窗开度.
An track-type pneumatic roof-vent opener for multi-span glass greenhouse was proposed and developed to avoid the slow response, of traditional gear-rack mechanism driven by electricity. Load of roof vents was calculated based on the greenhouse design standard of USA. Relationship of roof-vent opening, output force of cylinder and forces imposing on push rod with displacement of piston were analyzed by kinetic and kinematic dynamic simulation. The cylinder stroke and piston diameter were determined on the basis of analysis and calculation. Results indicated that there exists a maximal opening as for a specific pneumatic roof vent opener; required thrust of the cylinder is markedly influenced by the horizontal force between link rod and push rod, whereas friction influence is much smaller. The present opener is faster in response, more conveniently located and larger opening as compared with the traditional one.