Thermal Expansion Measurements on Operating Automobile Engines Using the MTII Accumeasure 1500 Capacitance Sensor

Table of Content

Introduction
Stresses on Engine Components
Accumeasure 1500 Capacitance Sensor
Results
Conclusion
About MTI Instruments

Introduction

With innovative developments in automobile engines (Figure 1), there is an increasing need to carry out additional testing procedures. Many components are available which are used for a number of applications to generate higher horsepower in a compact package. To meet this requirement, each component has to be developed to tighter tolerances. Oil pan is one such component (Figure 2).

Figure 1. Automobile engine

Figure 2. Oil pan

Stresses on Engine Components

Over the years, oil pan was mainly used as a reservoir for the engine lubricant, but there are some contemporary engines that use this oil pan as a structural component. This component is generally made from a strong aluminum or steel casting and then designed to support the rear main seal and the lower part of the crankshaft bearings. However, this latest development has results in a serious problem.

Engines constantly go through the heating and cooling cycles. As a result, it is important to ensure that both the oil pan and the engine block contract and expand at almost the same speed, or else the main seal, pan gasket and bearing races will be under constant strain. This in turn can promote premature bearing failures, oil leaks and unnecessary noise and vibration.

Accumeasure 1500 Capacitance Sensor

GM engineers were looking for a suitable solution to monitor the relative motion between the oil pan and the engine block. This technique would help in determining whether extreme stresses are occurring in the engine components. To address this issue, MTI Instruments, a company specializing in non-contact measurement systems, offered its Accumeasure 1500 capacitance sensor, which is known for its high precision and multi-channel capabilities.

To check the effectiveness of this sensor, a test was carried out in which 16 capacitance probes were tactically positioned on an engine. Each probe had better than 0.25µm resolution and came with a 0.04”operating range. The test was then started after setting all the outputs to zero volts. When the engine reached its operating temperature, the output of each sensor was noted down. This information was utilized to ascertain the relative displacement between the engine block and the oil pan.

Results

Test results revealed that the relative motion was within the acceptable seal and bearing specification set by manufacturers. However, the entire lower motor components would have to be redesigned if movements of 0.01” or greater are encountered.

Conclusion

MTI Instruments supplies a wide range of styles and types of non-contact capacitance sensor systems. The passive probes can withstand temperatures greater than 7600C) and thus provide exceptional thermal stability. The company also develops high precision fiber-optic systems and lasers with frequency responses up to 500kHz and resolutions up to 1nm. MTI Instruments also has a team of application engineers who provide practical and cost-effective solutions to complex measurement requirements.

About MTI Instruments

MTI Instruments is a worldwide leader in the design, manufacture and engineering of non-contact measurement systems and sensors.

MTII’s main products consist of computerized general gauging instruments for position, displacement, thickness and vibration applications based on laser triangulation, fiber-optic and capacitance measurement technologies.

The Semiconductor Products sensor group manufactures manual, semi-automated and fully automated wafer characterization tools designed to measure wafer thickness, total thickness variation (TTV), bow, warp and flatness of semi-insulating and semiconducting materials.

MTII’s Aviation Balancing Instruments group provides state-of-the-art portable balancing and vibration analysis systems for turboprop and jet aircraft engines.

This information has been sourced, reviewed and adapted from materials provided by MTI Instruments.

For more information on this source, please visit MTI Instruments.

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