TECHNICAL PAPERS: Internal Combustion Engines

On-Line Measurements of Engine Oil Aeration by X-Ray Absorption

[+] Author and Article Information
Devon Manz, Wai K. Cheng

Sloan Automotive Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139

J. Eng. Gas Turbines Power 129(1), 287-293 (May 24, 2006) (7 pages) doi:10.1115/1.2360604 History: Received February 06, 2006; Revised May 24, 2006

The oil aeration in a V-6 spark-ignition passenger car engine under motoring condition was measured by the X-ray absorption method in the speed range of 2000–6000 rpm. Measurements were made at different locations in the sump representing the state of the oil at (1) the pump inlet, (2) the head return, and (3) the timing chain return. The aeration of the block return was estimated from these measurements. At a fixed engine speed, the aeration (in % volume of air) of the head return and the chain return were about the same, and they were approximately twice the value found in the block return. This distribution did not change with engine speed. When weighted by the flow rate, however, the block return contributed to 55% of the aeration at the pump inlet; the total contribution of the head return and the chain return was 45% (36% from head return and 9% from chain return). Further aeration observations were made by comparing the cases with and without the oil sump windage tray in place. When the tray was removed, aeration at the pump inlet was found to increase by less than 30% for all speeds.

Copyright © 2007 by American Society of Mechanical Engineers
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Figure 1

Required integration time as a function of standard deviation in aeration measurement (σx) and count rates

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Figure 2

Air-X sensor signal as a function of oil temperature and the inferred relative density; SAE 5W-20 oil. The density was pegged at the published value at 15.6°C(60°F).

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Figure 3

Oil flow paths in the engine

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Figure 4

Geometry of oil flow in the sump. Top figure: view from top of sump with windage tray removed. Bottom figure: view from the bottom of the sump towards the top of the engine.

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Figure 5

Nonisokinetic sampling of oil flow. (a) Sampling rate smaller than the collection rate – spill over; (b) sampling rate faster than the collection rate – ingestion of air.

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Figure 6

Engine oil sampling points in the sump; the line drawing is to scale. The sampling locations were (1) sump pump inlet; (2) head return; (3) chain return. The glass view tube in the right picture was not used in this experiment.

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Figure 7

Typical aeration data from the three locations shown in Fig. 6. Engine speed ranged from 2000 to 6000rpm. Sample integration time of 5s; 1l∕min sample flow.

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Figure 8

Aeration measurement in a speed change. Measurement from sump pump inlet (location 1).

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Figure 9

Aeration at different engine speeds for locations 1 and 3 in Fig. 6. The four data points at each speed for each location correspond to the values obtained from the four procedures described in the text.

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Figure 10

Aeration at the sump pump inlet (location 1) for total engine oil volumes of 4.0, 4.5, and 5.0l (corresponding to 2.2, 2.7, and 3.2l of oil in the sump when engine was running)

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Figure 11

Aeration measurements as a function of engine speed at different locations in the sump

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Figure 12

Oil flow distribution in engine. Sump pump relief valve activated at 3000rpm.

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Figure 13

Distribution of air transport from the returns

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Figure 14

Aeration at sump pump inlet as a function of engine speed, with and without windage tray in place



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