Automotive Fuel Level Indicators - Report Example

Design Report Hall Effect Sensor Automotive Fuel Level Indicators Instrumentation and Measurement ENM2104 Confidentiality Notice Access to this document and referenced documents is provided to the recipient under the following conditions: 1) The contents are to be used solely for the purposes of the ENM2104 Unit at The School of Engineering, Edith Cowan University 2) The document will not be made accessible to any external party other than (if necessary) lecturers currently engaged by ECU under a contract which addresses confidentiality 3) Any requirement to vary these conditions is to be referred to the ENM2104 Unit Coordinator © Edith Cowan University 2014 Except as provided by the Copyright Act 1968, no part of this document may be reproduced, stored in a retrieval system or transmitted in any form or by any means without the prior written permission of the Edith Cowan University. Enquiries should be directed to the ENM2104 Unit Coordinator. Executive Summary Sensors have been incorporated into solving problems that are facing humans in their day to day lives. Apparently, this report looks into the incorporation of Hall Effect sensors within the automotive and transport industry for fuel level indication. The main advantage of this sensors being that they are accurate and durable even when the environment of existence is dirty. The scope involves the inclusion of a sensor identified by the code TLE4998P within a fuel tank for proximity checking purposes. The programming shall then be carried out to cater for temperature compensation and in the conversion of digital and voltage signals into data readable on a user interface that can be translated even by laymen. TABLE OF CONTENTS 1.Introduction 5 1.1. Description of the Project 5 2.Implementation 6 2.1. Abstracting the Problem 6 2.2. Division of Tasks 6 2.3. Problems Faced 7 3.Sensor Selection 8 3.1. Identification of the Sensor Type 8 3.2. Performance Test of the Sensor 9 4.Measurement System Implementation 10 4.1. Hardware Configuration 10 4.2. Software Configuration 10 5.Conclusion 11 6.References 12 7.Appendices 13 1. Introduction Automotive fuel level indicators are vital instruments that depict the amount of fuel remaining in a tank. These may also be deployed for checking liquid levels for underground storage tanks which are considered inaccessible for sounding purposes. The existing systems have however been found to be notoriously inaccurate thus the resolution to find other better means of measuring fuel levels. The old technique relies on analogue resistive gauges whose nature of operation is fast fading and become unfavourable for the future. This paper explores the potential deployment of Hall Effect Sensor in nulling the shame that drivers may face due to inaccuracies of the existing system of fuel level measurement. 1.1. Description of the Project This project seeks to find a suitable replacement for the analogue resistive automotive fuel level indicator which has proven to be inaccurate. The Hall Effect Sensor is based on magnetic field variation in order to vary the output voltage in a linear manner. Electricity is carried through a separate conductor which produces electromagnetism without interrupting the circuit. This is done through a wound core which surrounds the conductor to be measured. This system is applicable since the automotive fuel tank is constructed of ferromagnetic materials which can practically rely on this new technology. The working mechanism is that the Hall Effect Sensor shall be fixed at the top of the tank with a permanent magnet in place of the electromagnet in order to avoid any explosions. The magnetic field shall automatically increase on addition of fuel and vice versa when fuel reduces thereby resulting to a voltage increase and reduction respectively (Divakar, 2014). Figure 1: Hall Effect (Honeywell, 2013). 2. Implementation 2.1. Abstracting the Problem The problem with the existing fuel level indicators squarely lies in their inability to give an accurate feedback due to shifts in weather conditions and other environmental conditions that affect the resistivity of a given material. Temperature conditions for example are likely to lower or raise the resistance of the float type sensors which are considered as inferior to the Hall Effect Sensors. The gauge unit that is incorporated to the float type sensors is also considered as an analogue system that has to be overhauled owing to the digitization of most existing technologies. Therefore, this system shall be embedded with microcontrollers or microprocessors on the output section in order to provide the end user with an accurate digital user interface that is also friendly to laymen. 2.2. Division of Tasks The tasks of this instrumentation exercise shall be broken down as shown in the diagram below. First of all, it shall be important that the quantity to be measured be known in order to choose the correct sensor mechanism to be deployed since there exist several types of Hall Effect Sensors. Some of these sensors include linear hall sensors which can be used to measure level of fluid with regard to the major parameter (height) and rotating level sensors which are diametrically magnetized (Jain , 2012). Once the quantities have been established, the input interface of the sensor have to be designed in order to come up with a user friendly and readily integral system. The hall element should not however be ignored as this is the heart of this system thus an analysis should be carried out on the Hall Effect theory prior to digitization of the output. Once the nature of the output is established through mathematical analyses, it shall be tallied against the user interface values to ease the automation process. This shall be automatically be in form of electrical voltage which has to be converted to tank level for the end user to distinguish between an empty and a full tank while driving. Figure 1: Task division (Honeywell, 2013). 2.3. Problems Faced The major problem that this project faces during its execution period is the elimination of the electrical noise due to the long cable connection that shall be utilised. It is unfortunate that the conversion tables for this kind of corrections and adjustments are not standardized thus the project has to come up with its own tables of conversion for purposes of automation or coming up with the software part of it. The fact that this sensor is magnetic by nature translates to another problem that requires the area of enactment to be magnetic either in alloy or pure forms (Ramsden, 2006). This may however be countered by introducing ferromagnetic strips at the bottom of the tank. 3. Sensor Selection This section describes the type of sensor that shall be suitable for this exercise and how it shall be calibrated for perfect performance to be achieved. 3.1. Identification of the Sensor Type Due to the nature of the problem at hand, this exercise shall implement Infineon Hall Effect sensor TLE4998P that is EEPROM programmed for Pulse width modulation (PWM) interface. This sensor is produced basing on innovativeness of tried technologies in order to produce a product that conforms to IEEE standards. The stability of this product is also plausible and it is also durable in terms of sensitivity and signal processing concept. The signal is internally processed into a deterministic digital signal through a high precision analogue-to-digital signal conversion thus there is no need to introduce other forms of converting the electrical to digital. A stress sensor is also integrated within this important innovation for as a way of allowing constant monitoring of sensor over-moulding stresses and effects from the external environment. This sensor may also come with a package of other inbuilt sensors such as integrated lead frame capacitors that enhance the micro-break protection as a cost cutting mechanism. The PWM interface further offers cost cutting mechanism as the signal is converted into digital before being released for user interface rendering. Multiple signal conversion does not however allow for reverse conversion of digital information thus making this sensor a viable option of interest (Infineon Technologies AG, 2012). Figure 4: Configuration of TLE4998P3 Hall Effect Sensor (Infineon Technologies AG, 2008). 3.2. Performance Test of the Sensor Infineon Hall Effect sensor TLE4998P can be calibrated for performance using a special hardware that can access the random access memory (RAM). This allows for deterministic kind of EEPROM access in order to determine the performance of the sensor. In order to test against temperature performance, the software is incorporated with the access to check temperature of the sensor in order to aid the operator in establishing the workability of the sensor in extreme conditions such as heat or freezing temperatures. This information is picked from two pins i.e input or output combination which coincidentally are used to relay memory characteristics. This may also bring out some of the errors that the sensor might have been instilled with during manufacture. This may also be used to check for accidental programs due to environmental exposure of the sensor from time to time (Infineon Technologies AG, 2008). 4. Measurement System Implementation This section shall highlight the measurement system implementation together with the measurands, hardware configuration and software configuration for incorporation into the automotive system as an enhanced accuracy fuel indicator. 4.1. Hardware Configuration The hardware mainly comprises of the Hall Effect Sensor TLE4998P3which is planted on the top side of a fuel tank for positioning purpose. Unlike the analogue system of measurement, the liquid level is determined by the sensor which happens to have been movably positioned using a floating mechanism. The data storage mechanism is also provided for storing the calibrated values which convert the electric voltage and digital output into values that can be rendered on a modern digital display for viewing. The calculating means are also provided within the location float for comparison purposes between the calibrated values and the stored data. The last bit of hardware required for this configuration is a metal strip if the tank is not made of ferromagnetic materials that may make it possible for sensing or at least creation of a magnetic field that shall be responsible of raising or lowering the flowing voltage (Alaska Patent No. US5636548 A, 1994). 4.2. Software Configuration The processor unit that is to be incorporated for includes, clock 32, 34 and connector 36 with a support for a logic program as a measurand identifier and register. Power supply 42 is availed to the central processing unit (CPU) for digital data regulation. The Hall Effect Sensor uses connector 45 which us connected to connector 36 of processor 30 which is to be availed in groups of three sensors of this group. The temperature sensor that is incorporated for shift register separation via connector 36 permits connection via sensor probe as shown in appendix 2. The software is programmed to calibrate for voltage level that is relayed together with the data signal for counterchecking. This is also determined within the sensor as it incorporates a RAM that is programmed via EEPROM technology with the required command bits to convert electrical energy to digital data. The program stores the calibration values that can be in turn looked up in RAM 40 of a logic program. Six channels of the program possess the capability to compensate for recycled clock signal and environmental conditions such as temperature. The program is logically programmed to convert the information from RAM 40 into a probe scan routine against a string of program that renders the readings in terms of the fuel levels with respect to the tank dimensions that are keyed in. This is to say that the program is the main determinant of the liquid level which is effectively output to the user interface for reading by the driver or equipment user. 5. Conclusion The problem of accuracy in fuel level checking within the automotive and transport industry has been blamed for accidents. This may only be countered through the implementation of a conforming product whose nature of measurement is not affected by environmental effects such as temperature and space expansiveness. The conventional method of fuel measuring depends on the resistive materials in order to give a feedback on fuel level. This report successful explains on how Hall Effect sensors can be incorporated into measuring liquid level since it has a proximity sensing capability within ferromagnetic materials. The software section is also described within this report for purposes of systems automation and modernization/ digitization. 6. References Divakar, V. (2014). Fuel Gauge Sensing Technologies for Automotive Applications. International Journal of Advanced Research in Computer Engineering & Technology (IJARCET), 40-42. Dunn, W. D., & Traylor, L. G. (1994). Alaska Patent No. US5636548 A. Honeywell. (2013). Hall effect Sensing and application. Sensing and Control, 1-126. Infineon Technologies AG. (2008). TLE4998P3: Programmable Linear Hall Sensor. London: Infineon Technologies AG. Infineon Technologies AG. (2012). Sense & Control: Measuring Liquid Levels Using Hall Effect Sensors. London: Infineon Technologies AG. Jain , P. (2012, May 30). Level Sensors. Retrieved from Engineers Garage: http://www.engineersgarage.com/articles/what-is-level-sensor?page=4 Ramsden, E. (2006). Hall-Effect Sensors: Theory and Application. Oxford: Newnes. 7. Appendices Appendix 1 Appendix 2 Appendix 3 Read More