Browse Topic: Transmission gears
This paper focuses on the weak fault diagnosis of a dual - axes precision gear transmission system. Firstly, it elaborates on the structure and working principle of the system. Comprising components like azimuth and pitch channels, motors, and control units, the pitch channel's gear transmission chain is a key research area. Subsequently, fault modes and their harmfulness are analyzed. Different faults such as tooth surface wear and pitting are considered. These faults can lead to serious consequences like system failure and mission deviation. Based on this, a test system is constructed. It includes sensors and a data acquisition system to simulate faults and collect vibration signals. The signals are then analyzed to understand the system's behavior. Finally, a weak fault feature index based on time - domain entropy is developed. A threshold setting method based on severity index is also proposed. These methods together enable the accurate diagnosis of weak faults in the system, which
Gear shifting effort or force especially in manual transmission has been one of the key factors for subjective assessment in passenger vehicle segment. An optimum effort to shift into the gears creates a big difference in overall assessment of the vehicle. The gear shifting effort travels through the transmission shifting system that helps driver to shift between the different available gears as per the torque and speed demand. The shifting system is further divided into two sub-systems. 1. Peripheral system [Gear Shift Lever with knob and shift Cable Assembly] and Shift system inside the transmission [Shift Tower Assembly, Shift Forks, Hub and sleeve Assembly with keys, Gear Cones and Synchronizer Rings etc.] [1]. Both the systems have their own role in overall gear shifting effort. There has been work already done on evaluation of the transmission shifting system as whole for gear shifting effort with typical test bench layouts. Also, work has been on assessment of life of the
In conventional vehicles the shift strategy has a well-known impact on the system’s efficiency. An appropriate gear choice allows the internal combustion engine (ICE) to operate in efficient operating points (OPs) and thus contributes significantly to a reduced fuel consumption. Further efficiency improvements can be achieved by the hybridization of the powertrain. Due to the two propulsion systems, an additional degree of freedom arises, that requires an energy management strategy (EMS). The EMS controls the split of the requested power between the electric machine (EM) and the ICE. Accordingly, the system’s overall efficiency in hybrid electric vehicles (HEVs) is highly influenced by the quality of the EMS. This paper proposes to adapt an existing method for deriving fuel-optimal rule-based EMS by including the shift strategy for parallel HEVs. It is shown that fuel-optimal control can be achieved. The analytically derived look-up tables can be used to automatically calibrate in
With the increasing importance of electrified powertrains, electric motors and gear boxes become an important Noise Vibration & Harshness (NVH) source especially regarding whining noises in the high frequency range. Engine encapsulation noise treatments become often necessary and present some implementation, modeling as well as optimization issues due to complex environments with contact uncertainties, pass-throughs and critical uncovered areas. Relying purely on mass spring systems is often a too massive and relatively unefficient solution whenever the uncovered areas are dominant. Coverage is key and often a combination of hybrid backfoamed porous stiff shells with integral foams for highly complex shapes offer an optimized trade-off between acoustic performance, weight and costs. A dedicated experimental set-up has been designed in order to measure both structureborne and airborne NVH performances of engine encapsulation insulators applied on an engine casing placed in a coupled
Recently, as part of the effort to enhance fuel efficiency and reduce costs for eco-friendly vehicles, the R-gearless system has been implemented in the TMED (P)HEV system. Due to the removal of the reverse gear, a distinct backward driving method needs to be developed, allowing the Electronic Motor (e-Motor) system to facilitate backward movement in the TMED (P)HEV system. However, the capability of backward driving with the e-Motor is limited because of partial failure in the high-voltage system of an R-gearless system. Thus, we demonstrate that it is possible to improve backward driving problems by applying a new fail-safe strategy. In the event of a high-voltage battery system failure, backward driving can be achieved using the e-Motor with constant voltage control by the Hybrid Starter Generator (HSG), as proposed in this study. The introduction of feed-forward compensation for variable constant voltage control allows for the securement of more active output power within the
Vehicle transmission gear rattle is one of the most critical NVH irritants for refined vehicles. It is perceived more dominantly in lower gears of vehicle running. It depends on various design parameters like engine input torque amplitude & fluctuations, driveline torsional vibrations, gear micro & macro geometry, shaft flexibility, etc. Establishing exact contribution of each of these parameters to transmission rattle, thru experimental or simulation technique, is very challenging. Current paper explains the NVH CAE benchmark approach deployed to understand difference in rattle behavior of two transmission designs. Paper focuses on simulation of gear impact power and its sensitivity to transmission shaft deflections. Impact power is one of the indicators of transmission rattle noise and transmission shaft deflection is one of the contributors for gear impact power. 3D MBD simulations are carried out to calculate loose gear impact power by applying angular acceleration input to
Wet-sump transmissions are widely used in heavy duty and medium duty vehicles. As these transmissions do not have a dedicated forced lubrication system, it is important that the gear train, shafts, and enclosure are designed appropriately so that enough oil splashes to critical locations to ensure sufficient lubrication. The lubrication effectiveness of such transmissions can be studied through detailed tests or numerical simulations. Often, the vehicle, and therefore the transmission, encounters some severe operating conditions, such as climbing on an incline, driving downhill, etc. Studying these conditions through tests is an expensive process and this imposes the need for an analysis first approach. In this paper, the 3D multiphase Volume of Fluid (VOF) method is used to examine two such extreme cases: an 8-degree tilted installation of transmission in a vehicle, and an inclined condition of transmission during a 10-degree uphill climb. By studying the oil volume fraction on gears
This paper aims at analysing the effect of regeneration braking on the amount of energy harnessed during vehicle braking, coasting and its effect on the drive train components like gear, crown wheel pinion, spider gear & bearing etc. Regenerative braking systems (RBS) is an effective method of recovering the kinetic energy of the vehicle during braking condition and using this to recharge the batteries. In Battery Electric Vehicles (BEV), this harnessed energy is used for controlled charging of the high voltage batteries which will help in increasing the vehicle range eventually. Depending on the type of the powertrain architecture, components between motor output to the wheels will vary, i.e., in an e-axle, motor is coupled with a gear box which will be connected with differential and the wheels. Whereas in case of a central drive architecture, motor is coupled with gearbox which is connected with a propeller shaft and then the differential and to the wheels. All the components
In current competitive automobile sector, gear shift quality has become significant factor for vehicle evaluation. OEMs are sensibly focusing on improving gear shift quality to meet customer’s expectations. Though there are different gear shifting habits in different drivers, diagonal shifting is the fastest way of shifting gears in manual transmission vehicle. So the components linked with shift system should be designed to facilitate smooth diagonal gear shift pattern. This paper enlightens the process of defining chamfers on internal gear shifting components for smooth diagonal shifting movement of gear shift lever. It is hard to define chamfers by analytical or practical approach. Creo-mechanism is very useful simulation tool which can be used to understand diagonal shift patterns and to define the chamfers.
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