| Academic Open Internet Journal ISSN 1311-4360 |
Volume 17, 2006 |
Some conclusions about the appreciation of an injector system element
Vasil P.Vasilev, Emil S. Bogoslovov, Stancho K. Ådrev
University „Prof. À. Zlatarov”- Bourgas
Vasilev13@abv.bg
Abstract
By appreciation the λ-drill condition, optimal work of the injector system is guaranteed as well as maximum durability of motor and minimum level of noxious emissions in the atmosphere.
Keywords: λ-drill, injector system
Introduction
The λ-drill is one of the most important element by means of which a precise regulation of mixture composition of injector system has been made.
It generates voltage, depending on the difference between oxygen concentration of burned gasses and the fresh air. The λ-drill is installed in the outlet collector of the outmoded car models or in the exhaust tubes right in front of the catalyst of the new models.
The sensitive element in λ-drill is a ceramic body covered with ZrO2. The drill contacts by its surface with the burned gasses in the exhaust tube and by the other side surface contacts with the fresh air. When the temperature rises above 330° C on the both surface sides voltage is generated, depending on the oxygen concentration differences [ 1 ] .
This way the board electronic gets information about the burned gasses, respectively about the proportion fresh air- fuel and if the parameters do not correspond to the pre-set program, corrections of fuel injection has been made. When the fuel mixture is rich, the oxygen concentration is law and the drill generates high voltage up to 1V, when the fuel mixture is poor, the generated voltage is làw, about 0.05 ÷ 0.3V – fig.1. The voltage characteristic is very sharp – fig.2.
fig. 1
fig. 2
As far as the environment conservation is concerned, for the minimum level of noxious emission their stechiometric composition or the λ-proportion must be about zero. It is very important for the λ-drill to reach quickly the working temperature condition. That is way the modern car models are equipped with continuously heated λ-drills during work. For the newest advanced systems the heating has been done by the electronic block and it is controlled by the block. Planned drills made of TiO2 have been created. They work within the range of 0 ÷5 V (fig.3). Their sensibility is higher (fig.4). They also have been heated and controlled by the electronic block.
fig.3
fig.4
The longer the working time, the generating capacity of the drill decreases and it leads to considerable changes in the fuel mixture, the result is as follows:
1. Increased fuel consumption;
2. High level of noxious emissions;
3. Increasing motor oil level because of fuel infiltration as well as decreasing oil viscosity.
Because of fuel infiltration in the motor oil an intensive wearing of the crankshaft bearings, the piston hoops, the pistons and of the cylinders appears. As a result a quick motor defect may happen. That is why it is very important the λ-drill condition to be properly appreciated and if necessary to be substituted.
Suggested solutions:
The criteria for the λ-drill substitution conditions are the following:
The first criterion is the time for reaching a normal temperature regime, when the drill starts giving information for fuel mixture regulation. The optimal time for a drill without heating when cool motor has been started is 1.5 ÷ 3 min, while for drills with heating this time is 10 ÷ 30 sec. This control can be done by means of a multimeter or an oscilloscope plugged in the information drill cable.
The second criterion is the maximum voltage, generated by the drill at a maximally enriched fuel mixture. It is possible by sharply motor speeding up or compulsory fuel injecting in the suction collector. The voltage must be within the range of 0.65 ÷ 0.7V [3]. Further exploitation at lower values is not allowed.
The third criterion is the frequency of voltage changing. The good drills change their voltage about 60 times per min. (once per second). It is allowed the voltage to decrease 6 times per min. (once per 10 sec.) at a free motor regime. Although such a drill works good at high revolutions, at a free regime the motor works irregularly, ready to stop working because of the poor fuel mixture, than the revolutions increase because of too enriched mixture. That has a negative effect on the environment as well as on the fuel expense.
The fourth criterion is the heating element condition. Its resistance is 2 ÷ 20 Ω for the zirconey drills and 4 ÷ 10Ω for the titan drills [ 3 ]. At higher values the heating is diversed from the normal regime, while at a break down heating is not working at all.
For the planned λ-drills the electronic block emits stable voltage of 5V through the information cable to the drill and changes it from 4.5 to 0.1V [ 3 ].
When the drill has been weared, the two values approximate and when the levels 2V max and 1V min are reached, the drill has to be substituted.
Conclusion
à) The drill will function in normal regime if value parameters of the analyzed criteria are within the normal ranges.
b) Disturbed requirements of each criterion lead to drill substitution.
c) The analyzed criteria are taken for definite for the normal work from the service-station’s practice. All the results show that these criteria are definite for the λ-drill condition appreciation.
References
1. Luben Iliev, H. Stanchev, V. Ivanov, J. Ruseva, Electronic systems for automatic regulation of cars and car motors. „Technique” 1993
2. Workshop CD. The Netherlands,Vivid automotive date & Media, 1999.
3. ESI [tronic] Electronic Service Information Robert Bosch GmbH, Bosch Automotive Aftermarket. D-76225 Karlsruhe 2005.
Technical College - Bourgas,
All rights reserved,
© March, 2000