scholarly journals Experimental Investigation of the Seamless Gearshift Mechanism Using an Electric Motor and a Planetary Gear-Set

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6705
Author(s):  
Sun Je Kim ◽  
Kyung-Soo Kim
Keyword(s):  
Experimental Investigation ◽  
Electric Motor ◽  
Test Bench ◽  
Planetary Gear ◽  
Test Rig ◽  
Limited Size ◽  
Gear Shift ◽  
Operating Concept ◽  
Expected Performance ◽  
Vehicle Technology

Vehicle transmission which has discrete gear-stages inevitably produces torque drop during shifting gears. This torque drop should be minimized because it may lead to uncomfortable driving feeling and degradation of acceleration performance. In accordance with the spread of electric-powered vehicle technology, this study proposes novel transmission architecture to eliminate torque drop during shifting gears by using one electric motor and verifies its operating concept through experiments with a test-bench. The proposed transmission, called CGST (clutchless geared smart transmission) can synchronize the gear-shaft to be engaged for the next gear-stage with the output shaft by using a planetary gear-set and an electric motor. The CGST has a dual input gear-box with even and odd gear-stages on different input shafts, and the planetary gear-set and the electric motor control the speeds of each input shafts to smoothly engage the next gear-stage. This idea was verified by the simplified test-rig in this study. Three distinct scenarios for gear-shift including starting from engine idling, odd to even gear-shift, and even to odd gear-shift were conducted in the experiment. The shifting performance of the CGST was evaluated by comparing it with the results of the manual transmission (MT). As a result, the CGST shows only 24% of torque drop of the MT, and torque oscillation followed after gear-shifting is reduced by 26%. Although the developed test bench was of limited size, the possibility and expected performance of the CGST have been confirmed as the solution for seamless transmission.

Improvement of Turboshaft Restart Time Through an Experimental and Numerical Investigation

2020 ◽  
Author(s):  
Antoine Ferrand ◽  
Marc Bellenoue ◽  
Yves Bertin ◽  
Patrick Marconi
Keyword(s):  
Electric Motor ◽  
Thermodynamic Model ◽  
Sleep Mode ◽  
Test Rig ◽  
Gas Generator ◽  
Time Saving ◽  
Idle Speed ◽  
Flight Mode ◽  
Nominal Load ◽  
Turboshaft Engine

Abstract Inflight shutdown of one engine for twin-engine helicopters have proven beneficial for fuel consumption. A new flight mode is then considered, in which one engine is put into sleep mode (the gas generator is kept at a stabilized, sub-idle speed by means of an electric motor, with no combustion), while the second engine runs almost at nominal load. The ability to restart the engine in sleep mode is then critical for safety reasons. Indeed, the certification of this flight mode involves ensuring a close-to-zero failure rate for in-flight restarts as well as a fast restart capability of the shutdown engine. In this paper, the focus is made on improving the restart time of the shutdown turboshaft engine. Fast restart capability is necessary for flight management reasons. Indeed, in case of a failure of the engine operating close to nominal load while the other one is in sleep mode, there is no more power available and the helicopter can lose up to 15–20 meters per second during autorotation. The restart time becomes a critical parameter to limit the loss of altitude. In the configuration studied, the fast restart is achieved thanks to the electric motor designed to deliver a high torque to the gas generator shaft. This electric motor is powered by an additional battery, more powerful than the conventional one dedicated for standard restarts. The aim of the paper is to assess the potential restart time saving using an approach combining test rig data analysis and numerical results generated by a thermodynamic model able to simulate at very low rotational speed. A gas turbine engine starting process is composed of two main phases: the light-up phase and the acceleration phase. It is important to understand the detailed phenomenology of these two phases as well as the various sub-systems involved, first to highlight the influencing parameters of both phases and then to establish an exhaustive listing of the possible time optimizations. From the test rig campaign, conducted at Safran Helicopter Engines on a high power free turbine turboshaft engine, we are able to accurately break down the phases of the start-up sequence, which helps us to identify what steps of the sequence worth shortening. With the engine performance thermodynamic model, we can then use the information gathered from the test rig analysis to further predict how to save time and to give guidelines for developing new control strategies. The results of this study show that a fast restart going from sleep mode to max power speed can be up to 60% faster than a conventional restart going from sleep mode to idle speed. This is significantly faster, especially if one takes into account the higher final speed targeted by the fast restart.

Surface Topography and Noise Emission in Gearboxes

1997 ◽  
Author(s):  
Naser Amini ◽  
B. G. Rosén
Keyword(s):  
Experimental Investigation ◽  
Total Energy ◽  
Surface Topography ◽  
Noise Generation ◽  
Test Rig ◽  
Noise Emission ◽  
Applied Torque ◽  
Surface Topographies ◽  
Before And After ◽  
Noise Assessment

Abstract This paper, by the experimental investigation, deals with the effect of different surface topographies on noise generation in gears. Results from the noise assessment of one gear before and after honing are discussed. The honing operation was applied to the gear after the grinding. The gear was tested in an actual gearbox, operated in a test rig. Running conditions were systematically changed during the test; however, the same conditions were utilized for the gear before and after honing. The aim of the study was to identify the mechanism of the expected noise reduction, with surfaces being evaluated in 3D. The following results have been obtained: The total energy in the noise decreases significantly. The magnitude of the tooth-mesh frequency dose not change, but the level of its higher harmonics decreases significantly. These reductions are especially significant, when running at higher rotational speeds or when the applied torque is increased.

Experimental Investigation on Marine Main Shaft Bearings With Reduced Length to Diameter Ratio

2010 ◽  
Author(s):  
Wojciech Litwin
Keyword(s):  
Experimental Investigation ◽  
Working Conditions ◽  
Hydrodynamic Pressure ◽  
Diameter Ratio ◽  
Main Shaft ◽  
Test Rig ◽  
The Past ◽  
Flexible Support ◽  
Shaft Misalignment ◽  
Significant Bearing

Water lubricated bearings are often installed on new and modernized ships. The main reasons are: unit simplicity, no danger of pollution and low price. One of the main problems connected with this the bearings of this kind is defining maximum hydrodynamic film capacity. Due to very thin hydrodynamic film and significant bearing bush deformation, the EHL model should be used for calculations. Experimental research conducted in the past was carried out on a single bearing test rig [1, 2, 3]. Unfortunately that test rig has some disadvantages. Its flexible support gives possibility of shaft misalignment for instance in case of asymmetric hydrodynamic pressure film in the bearing. The new test rig, presented in this paper gives wide research possibilities and working conditions are very similar to those on a real ship.

Experimental Investigation of the Flow-Induced Vibrations of a Rod Cluster Control Assembly Inside Guides With Enlarged Gaps

2019 ◽  
Author(s):  
Pierre Moussou ◽  
Vincent Fichet ◽  
Luc Pastur ◽  
Constance Duhamel ◽  
Yannick Tampango
Keyword(s):  
Experimental Investigation ◽  
Flow Velocity ◽  
Nuclear Power ◽  
Axial Flow ◽  
Fretting Wear ◽  
Pressurized Water Reactor ◽  
Test Rig ◽  
Pressurized Water ◽  
Control Assembly ◽  
Control Rods

Abstract In order to better understand the mechanisms of fretting wear damage of guide cards in some Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP), an experimental investigation is undertaken at the Magaly facility in Le Creusot. The test rig consists of a complete Rod Cluster with eleven Guide Cards, submitted to axial flow inside a water tunnel. In order to mimic the effect of fretting wear, the four lower guide cards have enlarged gaps, so that the Control Rods are free to oscillate. The test rig is operated at ambient temperature and pressure, and Plexiglas walls can be arranged along its upper part, and a series of camera records the vibrations of the control rods above and below the guide cards. The vertical flow velocity is in the range of a few m/s. Beam-like pinned-pinned modes at about 5 Hz are observed, and oscillations of several mm of the central rods are measured, which come along with impacts at the higher flow velocities. A simple non-linear calculation reveals that the main effect of the impacts between Control Rods and Guide Cards is an increase of the natural frequency of the rods by about 10%. Furthermore, as the vibration spectra collapse remarkably well with the flow velocity, the experiments prove that turbulent forcing is responsible for the large oscillations of the control rods, no other mechanism being involved.

scholarly journals Dynamics and efficiency of planetary gear sets for hybrid powertrains

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1359-1368 ◽  
Author(s):  
M Mohammadpour ◽  
S Theodossiades ◽  
H Rahnejat
Keyword(s):  
Electric Motor ◽  
Hybrid Electric Vehicle ◽  
Combustion Engine ◽  
Planetary Gear ◽  
Transmission Efficiency ◽  
Drive Mode ◽  
Planetary Gear Sets ◽  
Hybrid Electric ◽  
Noise Vibration ◽  
Six Degree Of Freedom

The paper presents a tribo-dynamic model for planetary gear sets of hybrid-electric-vehicle configurations. The model comprises a six degree-of-freedom torsional multi-body dynamic system, as well as a tribological contact model in order to evaluate the lubricant film thickness, friction and efficiency of the meshing gear teeth contacts. The tribological model takes into account the non-Newtonian, thermal-mixed elastohydrodynamic regime of lubrication. Analysis is performed for a hybrid electric C-segment vehicle. The simulated conditions correspond to cases of power supplied by either the engine or the electric motor. The results illustrate that in the electric motor drive mode, improved noise, vibration and harshness refinement would be expected, whereas better transmission efficiency is achieved in the internal combustion engine drive mode.

A New Powertrain System for Electric Hybrid Vehicles

2014 ◽  
Vol 577 ◽  
pp. 408-411
Author(s):  
Ren Guang Wang ◽  
Ming Jun Zhang ◽  
Chuan Long Shi
Keyword(s):  
Electric Vehicle ◽  
Electric Motor ◽  
Planetary Gear ◽  
Hybrid Vehicles ◽  
Regenerative Braking ◽  
Power Train ◽  
Powertrain System ◽  
Electric Driving ◽  
Left And Right ◽  
Different Parts

A new powertrain system was developed for electric vehicle driving application with adoption of one electric motor and one set of planetary gear set. With the control of fork, the sleeve of synchronizer can mesh two different parts on the left and right side; the system can provide pure electric driving, hybrid driving and regenerative braking operation modes to meet vehicle practical conditions. It can reduce both power train structure size and cost with fewer parts.

Experimental Investigation of Local Heat Transfer Distribution on Smooth and Roughened Surfaces Under an Array of Angled Impinging Jets

2004 ◽  
Vol 127 (3) ◽  
pp. 532-544 ◽  
Author(s):  
Lamyaa A. El-Gabry ◽  
Deborah A. Kaminski
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Impinging Jets ◽  
Temperature Data ◽  
Test Rig ◽  
Surface Temperature Data

Measurements of the local heat transfer distribution on smooth and roughened surfaces under an array of angled impinging jets are presented. The test rig is designed to simulate impingement with crossflow in one direction. Jet angle is varied between 30, 60, and 90deg as measured from the target surface, which is either smooth or randomly roughened. Liquid crystal video thermography is used to capture surface temperature data at five different jet Reynolds numbers ranging between 15,000 and 35,000. The effect of jet angle, Reynolds number, gap, and surface roughness on heat transfer and pressure loss is determined along with the various interactions among these parameters.

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