Feasibility Study of an Oil-Free Turbocharger Supported on Gas Foil Bearings Via On-Road Tests of a Two-Liter Class Diesel Vehicle

This paper presents the feasibility study of an oil-free turbocharger (TC) supported on gas foil bearings (GFBs) via on-road tests of a 2-liter class diesel vehicle. The oil-free TC is constructed using a hollow rotor with a radial turbine at one end and a compressor impeller at the other end, a center housing with journal and thrust GFBs, and turbine and compressor casings. The oil-free TC reuses parts of a commercial variable geometry turbocharger, except for the rotor-bearing system. In a test rig driven by a diesel vehicle engine (EG), the rotordynamic performance of the oil-free TC is evaluated up to the rotor speed of 130 krpm, which is measured at the compressor end. The journal GFBs are modified to enhance the rotordynamic performance by inserting three metal shims between the bump-strip layers and bearing housing. The rotordynamic performance is also measured during on-road tests by replacing the original TC of the test diesel vehicle with the constructed oil-free TC. The journal GFBs have a relatively large bearing clearance and no metal shims to generate subsynchronous motions at low TC and EG speeds. During normal vehicle driving, the TC rotor motions show steady rotordynamic operations. The oil-free TC rotates at 25 krpm ∼ 50 krpm while the vehicle runs at 20 km/h ∼ 30 km/h on the road. Subsynchronous rotor motions initiate with a frequency of ∼100 Hz at the TC speed of ∼37 krpm. As expected, the TC rotor motion also shows multiple EG-induced harmonics. Upon external shocks, produced by driving the vehicle on road-bumps, the subsynchronous motions are only excited when the rotor rotates above the initiation speed of subsynchronous motion. The excitation is nondestructive because the vehicle suspension absorbs most of the external shock. Incidentally, the external shocks appear to have no influence on the synchronous motion and engine-induced harmonics of the TC rotor.

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Feasibility Study of an Oil-Free Turbocharger Supported on Gas Foil Bearings via On-Road Tests of a 2-Liter Class Diesel Vehicle

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-69586 ◽

2012 ◽

Cited By ~ 1

Author(s):

Kyuho Sim ◽

Suk Bum Kwon ◽

Tae Ho Kim ◽

Yong-Bok Lee

Keyword(s):

Feasibility Study ◽

Vehicle Suspension ◽

External Shocks ◽

Variable Geometry Turbocharger ◽

Foil Bearings ◽

Synchronous Motion ◽

Vehicle Engine ◽

Compressor Impeller ◽

Non Destructive ◽

Diesel Vehicle

This paper presents the feasibility study of an oil-free turbocharger (TC) supported on gas foil bearings (GFBs) via on-road tests of a 2-liter class diesel vehicle. The oil-free TC is constructed using a hollow rotor with a radial turbine at one end and a compressor impeller at the other end, a center housing with journal and thrust GFBs, and turbine and compressor casings. The oil-free TC reuses parts of a commercial variable geometry turbocharger except for the rotor-bearing system. In a test rig driven by a diesel vehicle engine (EG), the rotordynamic performance of the oil-free TC is evaluated up to the rotor speed of 130 krpm, while being measured at the compressor end. The journal GFBs are modified to enhance the rotordynamic performance by inserting three metal shims between the bump-strip layers and bearing housing. The rotordynamic performance is also measured during on-road tests by replacing the original TC of the test diesel vehicle with the constructed oil-free TC. The journal GFBs have a relatively large bearing clearance and no metal shims to generate sub-synchronous motions at low TC and EG speeds. During normal vehicle driving, the TC rotor motions show steady rotordynamic operations. The oil-free TC rotates at 25 krpm ∼50 krpm while the vehicle runs at 20 km/h ∼30 km/h on the roads. Sub-synchronous rotor motions initiate with a frequency of ∼100 Hz at the TC speed of ∼37 krpm. The TC rotor motion also shows multiple EG-induced harmonics, as expected. Upon external shocks given by passing the vehicle on road-bumps, the sub-synchronous motions are excited only when the rotor rotates above the initiation speed of sub-synchronous motion. The excitation is non-destructive because the vehicle suspension absorbs most of the external shock. Incidentally, the external shocks appear to have no influence on the synchronous motion and engine-induced harmonics of the TC rotor.

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Development and Performance Measurement of Oil-Free Turbocharger Supported on Gas Foil Bearings

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4004719 ◽

2012 ◽

Vol 134 (3) ◽

Cited By ~ 15

Author(s):

Yong-Bok Lee ◽

Dong-Jin Park ◽

Tae Ho Kim ◽

Kyuho Sim

Keyword(s):

Power Loss ◽

Time Delays ◽

Operating Conditions ◽

Total Power ◽

Stable Operation ◽

Compressor Wheel ◽

Foil Bearings ◽

Vehicle Engine ◽

Turbine Inlet ◽

Diesel Vehicle

This paper present the development of an oil-free turbocharger (TC) supported on gas foil bearings (GFBs) and its performance evaluation in a test rig driven by a diesel vehicle engine (EG). The rotor-bearing system was designed via a rotordynamic analysis with dynamic force coefficients derived from the analysis of the GFBs. The developed oil-free TC was designed using a hollow rotor with a radial turbine at one end and a compressor wheel at the other end, a center housing with journal and thrust GFBs, and turbine and compressor casings. Preliminary tests driven by pressurized shop air at room temperature demonstrated relatively stable operation up to a TC speed of 90,000 rpm, accompanied by a dominant synchronous motion of ∼20 μm and small subsynchronous motions of less than 2 μm at the higher end of the speed range. Under realistic operating conditions with a diesel vehicle engine at a maximum TC speed of 136,000 rpm and a maximum EG speed of 3140 rpm, EG and TC speeds and gas flow properties were measured. The measured time responses of the TC speed and the turbine inlet pressure demonstrated time delays of ∼3.9 and ∼1.3 s from that of the EG speed during consecutive stepwise EG speed changes, implying the GFB friction and rotor inertia led to time delays of ∼2.6 s. The measured pressures and temperatures showed trends following second-order polynomials against EG speed. Regarding TC efficiency, 4.3 kW of mechanical power was supplied by the turbine and 3.3 kW was consumed by the compressor at the top speed of 136,000 rpm, and the power loss reached 22% of the turbine power. Furthermore, the estimated GFB power losses from the GFB analysis were approximately 25% of the total power loss at higher speeds, indicating the remainder of the power loss resulted from heat transfer from the exhaust gas to the surrounding solid structures. Incidentally, as the TC speed was increased from 45,000 to 136,000 rpm, the estimated turbine inlet power increased from 19 to 79 kW, the compressor exit power increased from 7 to 26 kW, and the TC output mass flow rate from the compressor increased from 21 to 74 g/s. The average TC compressor exit power was estimated at ∼34% of the turbine inlet power over this range.

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The Used of Pedal-Pad Effective Amplitude Transmissibility Value to Predict Size of Comfortable Pedal-Pads

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.471.52 ◽

2013 ◽

Vol 471 ◽

pp. 52-58

Author(s):

A.R. Yusoff ◽

Baba M. Deros ◽

D.D.I. Daruis

Keyword(s):

Root Mean Square ◽

Health Problems ◽

Constant Speed ◽

Mean Square ◽

Car Body ◽

The Road ◽

Vehicle Engine ◽

Vibration Transmissibility ◽

On The Road

Vibration transmissibility from a car body to pedal-pad could result to drivers discomfort and fatigue, which may lead to health problems. Vibration transmissibility occurs when the vehicle engine is turned on and vibration is transmitted from the car body to pedal-pad in this research Pedal-pad effective Amplitude Transmissibility (PEAT) value was used to predict suitable size of the pedal-pad that could provide comfortable operation of the pedal. In this study, the variables are the three different sizes of pedal-pads and data was recorded while the car was moving on the road at constant speed with three different sizes of pedal-pads. The data was measured in root mean square (r.m.s) unit, of the frequency weighted acceleration (m/s2) for every minute. The finding of the study shows that percentage PEATr.m.s of the three different sizes of pedal-pad is greater than 100%. It shows that vibrations to pedal-pads are greater than vibration from the car body consequentially it means that the foot on the pedal is exposed to higher vibration transmissibility than the foot on the floor.

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Diesel Vehicle with Ultra-Low NOx Emissions on the Road

10.4271/2019-24-0145 ◽

2019 ◽

Cited By ~ 2

Author(s):

Joachim Demuynck ◽

Cecile Favre ◽

Dirk Bosteels ◽

Frank Bunar ◽

Joachim Spitta ◽

...

Keyword(s):

Nox Emissions ◽

The Road ◽

On The Road ◽

Diesel Vehicle

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Particle Number Emissions of a Diesel Vehicle during and between Regeneration Events

Catalysts ◽

10.3390/catal10050587 ◽

2020 ◽

Vol 10 (5) ◽

pp. 587 ◽

Cited By ~ 7

Author(s):

Barouch Giechaskiel

Keyword(s):

Particle Number ◽

Catalytic Reduction ◽

Ambient Air ◽

Diesel Particulate ◽

Particulate Filters ◽

The Road ◽

Diesel Vehicles ◽

On The Road ◽

Cold Starts ◽

Diesel Vehicle

All modern diesel vehicles in Europe are equipped with diesel particulate filters (DPFs) and their particle number (PN) emissions at the tailpipe are close to ambient air levels. After the Dieselgate scandal for high NOx emissions of diesel vehicles on the road, the high PN emissions during regeneration events are on the focus. The PN emissions of a diesel vehicle on the road and in the laboratory with or without regeneration events were measured using systems with evaporation tubes and catalytic strippers and counters with lower sizes of 23, 10 and 4 nm. The tests showed significant PN levels only during engine cold starts with a big fraction of sub-23 nm particles during the first minute. After the first seconds the sub-23 nm fraction was negligible. Urea injection at the selective catalytic reduction (SCR) for NOx system did not affect the PN levels and the sub-23 nm fraction. The emissions during regeneration events were higher than the PN limit, but rapidly decreased 2-3 orders of magnitude below the limit after the regeneration. Artificially high sub-10 nm levels were seen during the regeneration (volatile artifact) at the system with the evaporation tube. The regenerations were forced every 100–350 km and the overall emissions including the regeneration events were two to four times lower than the current laboratory PN limit. The results of this study confirmed the efficiency of DPFs under laboratory and on-road driving conditions.

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