汽油发动机新型动力传输系统设计与研究

汽油发动机新型动力传输系统设计与研究

硕士研究生学位论文摘要I

摘要

目前曲柄连杆机构广泛用于车发动机的功率传递和运动形式转换，由于自身承载能力强，往复运动可靠，以及周期性好等优点被用做内燃机的热功转换机构上，但是采用这种机构的内燃机存在单位体积功率受到限制，活塞的高次往复惯性力幅值较大，多次项无法平衡，活塞裙部侧压力容易引起拉缸等诸多缺陷。

本文提出了一种新型的发动机动力传输机构，主要是以不完整齿轮齿条结合摆杆超越离合器来实现传统曲柄连杆的功用。重点论述不完整齿轮齿条如何实现四个行程，摆杆结合单向超越离合器怎样驱动输出直轴。将传统的曲柄连杆的作功行程分离出来以摆杆摆动代替，同时从机构受力的角度对比分析曲柄连杆的一些固有的劣势，从而说明新型动力传输系统优势所在，对提高机械效率、燃油经济性、节约能源有重要的指导意义。本文的主要研究内容有以下几个方面：

（1）对传统的曲柄连杆进行力学分析。阐明其应用的优势和劣势所在，从曲柄连杆的压力角和传动角与作功行程的协调性的方面出发，解释它的不足。应用Fluent6.3加以辅助分析，可以更为直观的观察汽缸内压力、速度、密度等参数的各种变化情况，从实际论证前面理论分析的正确性。

（2）提出新型发动机的基本构想，完成相关理论计算。在提高齿条换向的啮合准确性和稳定性上，给出相应的可行措施，保证换向的平稳有序。不完整齿轮采用不等长啮合弧来改变行程位移，从而提高废气的排净度，并使用辅助汽缸预混合来进一步增强混合气的燃烧性，达到增大功率的目的。合理的选择摆杆限位槽孔的长度，摆杆结合单向超越离合器应用于输出直轴，说明它们的作用和创新之处，并解释摆杆在限位和保护机构两方面的应用。对整个动力传输机构的机械效率进行分析讨论，重点讨论进气、压缩、排气三个行程不完整齿轮齿条的啮合过程和做功行程的摆杆效率。

（3）利用ADAMS对不完整齿轮齿条换向往复机构进行运动学和动力学分析。有效解决不完整齿轮和齿条的约束处理，运用单侧碰撞函数impact实现对四个冲程的控制，介绍主要参数的选定，确保齿轮齿条能按照实际啮合进行运动。分别分析不完整齿轮、齿条和轴在不同转速下的响应特性，以位移、速度、受力等数据为研究对象，给出提高机构换向可靠性和准确性的方法。

（4）实验装置的设计、制造、安装、调试。使用变频电机带动齿轮运动来实现四冲程，通过配套变频器调节控制电机的输出转速，以模拟不同转速下不完整齿轮齿条的啮合过程，对比理论推导，找出机构的新颖之处和不足，并对不足之处进行改进分析。

关键词：动力传输机构；不完整齿轮；齿条；摆杆；超越离合器；效率

II 摘要硕士研究生学位论文

At present, the crank and connecting rod mechanism is widely used in car engine power transfer and movement form conversion because of its high bearing capacity, reliable reciprocating motion, the advantages of good cycle. And it is used in thermal conversion mechanism for internal combustion engine, but the engine of this mechanism has many defects, for instance, the power per unit volume is limited, the higher order reciprocating inertia force amplitude is larger, multiple items cannot balance, the piston skirt side pressure is easy to cause the scuffing of cylinder bore and so on.

This paper presents a new power transmission mechanism, which is mainly based on the incomplete gear, the rack with the swing rod, the overrunning clutch to realize the function of traditional crank and connecting rod. It focuses on the incomplete gear, the rack how to realize four strokes, the swing rod with unidirectional overrunning clutch how to drive output shaft. That uses the swinging of the swing rod instead of traditional the crank and connecting rod power stroke, contrast stress analysis of crank connecting rod analyses some inherent disadvantages at the same time so that it explains the advantages of the new power transmission system, which has an important guiding significance on improving the mechanical efficiency, fuel economy, saving energy. The main contents research of this paper includes the following aspects:

(1) Mechanics analysis of the traditional crank and connecting rod. Discuss the advantages and disadvantages of its application, it can explain insufficient from the coordination in the pressure angle and the transmission and the power stroke of the crank angle and connecting rod aspects. Application of Fluent6.3 is analyzed; the parameters can be observed directly in the cylinder, such as pressure, velocity and density etc, the correct front theory analysis is proved from the fact.

(2) Put forward the basic conception of new engine, and implement relevant theory. To improve the accuracy and stability of the rack reversing meshing, feasible measures are given to ensure the smooth and orderly reversing. The incomplete gear use unequal mesh arc to change the displacement so as to improve the purity of exhaust gas, and the use of auxiliary cylinder premixed enhance the combustion of mixed gas further, it achieves a target that increases the power. Reasonable choice of the swing rod limiting slot length, swing rod with unidirectional overrunning clutch are applied to the output shaft, which explain their role and innovation, and it explains two aspects of the limit and protection mechanism in the swing rod application. The mechanical efficiency of the power transmission mechanism are discussed, it focuses on the