内燃机缸套活塞环系统的摩擦学设计

本文在系统思想的指导下,采用理论分析与润滑计算相结合,对内燃机摩擦副缸套一活塞环系统在正常工作时的摩擦,润滑、磨损等摩擦学行为进行了探讨,并根据研究结果。以桶面环为对象,以Ｓ１９５单缸紫机机的参数为例,编掉了通用内燃机摩这设计软件,以实现对内燃机缸套一活塞环系统的摩擦学设计和使用效果的预测。     

Bench Wear Testing of Common Gasoline Engine Cylinder Bore Surface/Piston Ring Combinations

In this study, two bench wear tests, the Cameron-Plint modified lest (C-P) and the Electro-Mechanical test (LS9), have been used to evaluate common internal combustion engine cylinder bore surface/piston ring pairs. Bore, materials tested include cast iron, 390 aluminum, and Nikasil. Piston rings tested include chromium-plated, plasma-sprayed molybdenum, and gas-nitrided stainless steel. Both the C-P and LS9 bench wear tests showed the same general trends. Gas-nitrided stainless steel rings provide the lowest overall ring wear and the lowest cast iron bore wear. 390 bore wear is higher than that of cast iron or Nikasil. Chromium-plated or gas-nitrided stainless steel rings provide the best balance of ring and bore wear against 390 aluminum, while molybdenum rings against 390 produce the worst combined wear. Differences in wear rates for 390 aluminum are related to variations in temperature and lubrication rate between the two testers. Bore wear measurement accuracy is quantified and an improved measurement technique is introduced. An initial study of surface finish effects shows that an increase in roughness increases the friction coefficient.     

Friction Power Loss Simulation of Internal Combustion Engines Considering Mixed Lubricated Radial Slider,Axial Slider and Piston to Liner Contacts

Different types of mixed lubricated contacts are present in internal combustion engines. These are several radial slider bearings; for instance, in main bearings; big end, small end, and piston pin bearings; as well as axial slider bearings and piston–liner contacts. Phenomena such as friction power loss and wear as well as acoustic excitation and oil consumption of the overall lubrication system are mainly affected by these contacts. Therefore, the simulation-based investigation of oil film–lubricated contacts is important during the development process of internal combustion engines. Due to the highly nonlinear interactions, the applied mathematical models have to consider the dynamics of the overall flexible body system in addition to the detailed properties of the contacts and the lubricant itself.

This work outlines both the theory of the separated mathematical models and their coupling. The large number of nonlinear contacts, which is possible to consider when applying the presented coupling approach, is emphasized. Furthermore, application of a friction power loss analysis for an in-line four-cylinder internal combustion engine is described.     

The Experimental Study of Laser Microprecision Treatment of I. C. Engine Tappet

The cam-tappet of an I. C. engine is a rubbing pair with high load and severe lubrication condition. In order to raise the anti-scuffing capacity of the cam-tappet, a laser microprecision treatment was adopted to make the topography with artificial regular asperities on the working surface of tappets. It was proved by experiment rising a full-scale engine rig that the tappets treated by laser microprecision had an obvious antiscuffing effect.     

Calculation of Journal Bearing Dynamic Characteristics Including Journal Misalignment and Bearing Structural Deformation©

A detailed journal bearing analysis for accurate evaluation of film dynamic characteristics is presented. The new formulation is based on a local perturbation of the oil film at each computational node that captures the important effects of journal misalignment and bearing structural deformation in rotor dynamics and engine NVH applications. The new algorithm is an extension to the classical approach of evaluating film dynamic characteristics based on journal eccentricity perturbation. The governing equations for the oil film pressure, stiffness, and damping are solved using a finite difference approach and their output is validated with numerical results from the literature.     

The Effects of Cylinder Wall Surface Roughness and Bore Distortion on Blow-by in Automotive Engines

A laboratory test device, was developed to study the effects of cylinder wall, surface roughness and bore, distortion on blow-by in automotive engines. The test device was constructed of components from a four-cylinder engine with a test box welded into the engine block to take the place of one of the cylinders. Removable liners used in the lest box were honed to varying surface roughnesses and bore distortion levels, Blow-by, used as a measure of conformance between the piston rings and cylinder walls, was found to increase at the end of the test with increasing initial distortion and initial surface roughness.     

Two-Dimensional Piston Ring Lubrication—Part II: Elastic Ring Consideration

A two-dimensional analysis for piston ring lubrication is presented by considering elastic deflection, EHL and cavitation effects. A numerical procedure is developed for solving hydrodynamic pressure and oil film, thickness shape due to ring deflection and elastic deformation. An elliptic cylinder liner and elastic ring are considered to investigate the circumferential flow effect which has been ignored in previous studies. Results for a typical automotive engine demonstrates that the elastic deflection and deformation of the piston ring have a tendency to reduce the gap caused by the noncircular cylinder. Under the high combustion chamber pressure, the minimum film thickness tends to have a uniform value in the circumferential direction. In turn, this provides a level of control of circumferential flow when the combustion chamber pressure is low. However, the elastic deflection of the piston ring always creates a potential for large blow-by around the piston ring gap area when the cylinder is non-circular. The two-dimensional analysis presented also reveals a reduction of piston ring oil film thickness due to the circumferential flow compared to one-dimensional analysis.     

Journal Design Considerations for Turbomachine Shafts Supported on Foil Air Bearings

Foil air bearings can offer substantial improvements over traditional rolling element bearings in many applications and are attractive as a replacement to enable the development of advanced oil-free turbomachinery. In the course of rigorous testing of foil journal bearings at NASA Glenn Research Center, shaft failure was repeatedly encountered at high ambient temperature and rotational speed, with moderate radial load. The cause of failure is determined to be excessive non-uniform shaft growth, which increases localized viscous heating in the gas film and eventually leads to a high-speed rub and destruction of the bearing and journal. Centrifugal loading of imbalance correction weights and axial temperature gradients within the journal due to the hydrodynamic nature of the foil bearings, determined by experiment and finite element analysis, are shown to be responsible for the non-uniform growth. Qualitative journal design guidance is given to aid in failure prevention.     

柴油发动机活塞熔顶开裂失效分析

某机型活塞在特定地域市场上出现活塞熔顶及活塞开裂的故障现象。从活塞的材料结构、配缸间隙、活塞的冷却、发动机运行工况等方面分析故障现象,使用FEA分析工具及发动机试验等,通过加强活塞冷却、优化油泵喷油量、控制油气分离器工艺过程,有效解决活塞开裂问题。     

齿条带活塞总成旋铆结构设计与分析

在分析齿条活塞卡簧结构原理的同时,着重阐述一种新型的齿条活塞旋铆结构。它利用金属塑性变形的特性,通过设计一种新型活塞环体和使用专用的工装(旋铆夹具和铆压轮),实现了齿条与活塞环体的刚性连接,从根本上解决了齿式液压助力转向器发卡故障,增大了安全系数。     

The Performance of a Hybrid Ceramic Ball Bearing Under High Speed Conditions with the Under-Race Lubrication Method

Large bore (150 mm) hybrid ceramic ball bearings and all-M50 steel bearings were tested with under-race lubrication to compare the heat generation and the temperature rise at speeds up to 2.25 million DN. Furthermore, oil shut-off tests were carried out with both bearings over 2.25 million DN.

The experimental results of the heat generation for both bearings were nearly the same at an axial load of 19.6 kN. at 34.3 kN, the heat generation of the hybrid bearing was lower than that of the M50 steel bearing at low speed. The heat generation of both bearings gradually approached each other with increasing speed and became nearly equal at a speed of 15,000 rpm. The survivability of the hybrid bearing in the oil shut-off test was superior to that of the M50 bearing. These experimental results were explained by the calculation results using a computer analysis software which simulates the kinematics and the performance of ball bearings.     

一种发动机装配线活塞油环分环机构的设计

对一种发动机活塞环装配机进行了分析,针对其结构缺陷设计了一个灵巧的油环分环机构,解决了因装配过程中卡环、推板易磨损等一系列问题。     

汽车离合器柱塞式助力泵的改进设计

汽车离合器助力泵在中、重型载货汽车上应用广泛。文中对现有离合器柱塞式助力泵做了一定的机构改进。     

Hydro-Roll: A Novel Bearing Design with Superior Thermal Characteristics

A novel journal bearing design, called hydro-roll, which combines a hydrodynamic journal bearing with a rolling-element bearing in series, is presented. The hydro-roll principally operates as a rolling-element bearing at low speeds and as a hydrodynamic bearing at high speed. When properly designed, the hydro-roll can offer superior performance over the conventional hydrodynamic bearing in terms of both wear and thermal characteristics. The hydro-roll prevents the severe wear which occurs during the start-up of hydrodynamic journal bearings since it operates as a rolling-element bearing whenever the sliding friction is too high. This characteristic has the important advantage of reducing the risk of catastrophic failure by bearing seizure.

At a steady high speed, the hydro-roll operates as a hydrodynamic journal bearing while the sleeve together with the inner race of the rolling-element bearing turn at a low speed. This study focuses on the thermal analysis of a journal bearing with a rotating sleeve in comparison to an identical stationary sleeve. The results indicate that the sleeve rotation reduces the risk of bearing failure due to local overheating of the sleeve. The minimum sleeve speed required for this effect is evaluated.     

IBooster总成工作性能检测系统设计

设计了一套基于CAN通信的IBooster总成工作性能检测系统。基于伺服电缸设计了加载系统,实现电缸加载速度与位移的精确调控;基于研华数据采集卡和CAN通讯卡设计了数据采集系统,实现对传感器与IBooster总成的数据采集与监测;工控机完成IBooster总成工作性能特性曲线绘制及测试结果获取;采用真空注油、泵循环注油和正压注油等多重注油方式,保证测试系统内部空气充分排出,提高测试结果的准确性。多次试验表明,该系统能够准确检测IBooster总成的工作性能,满足生产厂家的使用需求。     

HXQ活塞式蓄能器的结构改进设计

介绍了HXQ活塞式蓄能器的结构和工作原理,分析了活塞式蓄能器启动压力偏大,内泄漏的原因,并提出了改进措施。     

装配线活塞销卡环压装设备优化

在发动机装配过程中,活塞销卡环的装配至为关键。一旦活塞销卡环出现装配问题,在发动机工作过程中卡环有可能发生松动甚至脱落,进而引发严重后果。针对目前Comau设备存在啃活塞的质量问题以及压头损坏率极高的高维护成本问题,通过对设备的工作原理、零件特点以及问题现象进行综合分析,从结构和控制逻辑对设备进行优化,从而保证了卡环压装的稳定性,减少了压头的更换频次,提升了卡环的装配质量。     

XM-E36斜盘式柱塞马达的改进设计

该文主要介绍了传统柱塞马达柱塞回程的缺点,通过对回程机构的改进设计,彻底解决了传统斜盘式柱塞马达的回程弹簧断裂问题,使得该马达不仅简化了结构降低了成本而且大大地延长了使用寿命.     

A Study of Dynamically Loaded Finite Journal Bearings in Mixed Lubrication Using a Transient Thermohydrodynamic Analysis

A transient analysis of dynamically loaded finite journal bearings in mixed lubrication is made by solving the modified generalized Reynolds equation, 2-D energy equation in the oil, and heat conduction equation in the journal simultaneously including mass conserving cavitation. ISOADI (isothermal shaft and adiabatic bushing inner surface) thermal boundary condition is used. Journal temperature is treated as quasi-steady over one loading cycle. Two kinds of contact model are used. Numerical solutions using the finite difference method are presented. Results shows that the bearing behavior is closely tied to the roughness texture and topography, asperity contact load, bearing geometry, and operating conditions.