Effect of Tooth Surface Modification on Dynamic Transmission Efficiency of Double Helical Gear Trains

To analyse the influence mechanism of vibration loads on dynamic transmission efficiency (DTEF) of double helical gear trains (DHGT), a calculation method of DTEF which takes into consideration the real-time dynamic loads is proposed from the perspective of improving both efficiency and precision. The average DTEF is taken as the dynamic objective function of optimization for three-dimensional modification technology of tooth surface. An engineering example is given in form of numerical simulation, which proves that the average DTEF with the consideration of dynamic loads is obviously lower than the static transmission efficiency (STEF), especially for the resonance speed region. The results also show that the DTEF after 3-D modification is significantly improved, owing to the improvement of meshing state of tooth surface. The comparison of DTEF with different loads and speeds via simulation and experiment furtherly demonstrates the credibility of this theoretical perspectives. This study gives the explanation on the importance of DTEF in determination of driveline parameters and estimation of transmission quality of DHGT. The developed method for DTEF analysis is practical in engineering, and establishes a reliable foundation for further research on design of high-quality double helical gear trains.

MEANS, STANDS AND MACHINES FOR TESTING GEAR WHEELS AND GEAR TRAINS OF HELICOPTER REDUCTION TRAINS

The production and repair of such high-tech and important products as helicopters‟ reduction trains is impossible without comprehensive testing of these products, starting with the manufacture of their individual parts and assemblies and ending with the delivery of reduction trains to the customer. Various means for testing of gear wheels‟ rims and gear trains of helicopter‟s reduction trains, which have found application in testing equipment, are presented. Devices, testers, stands and machines for various tests are considered in order to control the characteristics of gear trains of aviation reduction trains after certain periods of their operation and repair, aimed at achieving better performance during further operation. The considered traditional metrological means of control of gear rims, gear measuring machines and complexes, some stands and machines for testing of reduction trains, pulse controllers and roll machines give an idea of various methods and means of control of gear wheels and gear trains of helicopters‟ reduction trains. The main method of experimental research of gear trains of reducers is stand tests both on movable gear wheels and on roll machines. Until recently, the most common method for monitoring and diagnosing gear trains has been vibrography, however, existing techniques do not give an accurate picture of the train condition, especially the contact surface of the teeth. During the operation of the gear train as a part of the helicopter‟s reduction train, signals from other sources (rotors, blades, shafts, bearings) are superimposed on the vibration signal generated by the gear train which significantly complicates the extraction and processing of the desired vibration signal. One of the most effective methods for monitoring and diagnosing the technical condition of kinematic chains of different complexity, which includes gear trains of helicopters„ reducers is kinematometry. The disadvantage of traditional kinematometry is the need to use high-precision sensors for the frequency and phase of the rotor rotation. Control of vibration from the early 1990s to the present time is the most advanced control, the means and methods of which are well developed in the aviation industry.

Auto Gear Teeth Burnishing Machine Using Servo Control

A typical vehicle transmission is comprised of between five and six gear sets and a series of gear trains that allows a driver to control how much power is delivered to the vehicle without changing how fast the engine runs. This transmission makes noise such as burrs, nicks, high points and heat treat scales are the leading causes of noise in power transmission. There are many different causes of gear noise, all of them theoretically preventable. Unfortunately, the prevention methods can be costly, both in equipment and manpower. If the design of the gear and its application are appropriate, in theory all that is necessary is to have a tight control on the process of producing the finished gear. In reality, there are many variables that can cause a process, no matter how well-controlled, to deteriorate, and thus cause errors, some of which will cause a gear to produce unwanted noise when put to use. The effective way to eliminate this noise the process known as "Gear Burnishing". The proposed system uses gear shaving cutter as a master for burnishing or deburring operation of gear teeth with servo mechanism (includes servo motor and servo drivers), Programmable logic controller (PLC), Human machine interface (HMI) to remove gear inaccuracies and so as to reduce or eliminate transmission noise and provide more life and reliability to transmissions in vehicles resulted into noise free vehicles.

Performance Evaluation of a Compound Power-Split CVT for Hybrid Powertrains

The Power-Split Continuously Variable Transmission is one of the most promising architectures for Hybrid Electric Vehicles. These systems have been introduced to improve vehicle global efficiency since they can maximize the efficiency in varying operating conditions. During the design stage, the availability of modeling tools would play a key role in achieving optimal design and control of these architectures. In this work, a compound power split device that combines an electric Continuously Variable Transmission with two planetary gear trains is analyzed. A comprehensive model is derived that allows the different power flow configurations to be evaluated given the properties of the single subcomponents of the system. The efficiency of the powertrain can be derived as well, and a numerical example is provided. The architecture studied has an efficiency that can be higher than that obtained using one single eCVT for most of the global transmission ratio range, showing that this solution could be suitable as a part of a more complex compound transmission that engages in a specific speed range.