impact of ethanol on fuel injection pump of diesel engine

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ENGINEERING FOR RURAL DEVELOPMENT Jelgava, 26.-27.05.2011.the tests and measurements was n fp =800 rpm, based on the rotational speed <strong>of</strong> the test engine equippedwith a fuel injection pump and operating at rated power n e =1600 rpm. The fuel section capacity waschecked separately for each section and the duration <strong>of</strong> one measurement was n c =800 operating cycles.The fuel quantity was measured in cm 3 .Results and discussionThe technical condition <strong>of</strong> the fuel-supply equipment can be evaluated by means <strong>of</strong> the sectioncapacity. If the capacity complies with the values indicated in the technical specifications, the enginereceives the required amount <strong>of</strong> fuel in every operating mode, provided that the regulator <strong>of</strong> the fuelinjection pump and other subsystems are in good order. The results <strong>of</strong> section capacity measurementcarried out in the course <strong>of</strong> the test are shown in Figure 3.The test results reveal that when using the stand liquid and <strong>ethanol</strong> in the fuel injection pumpthere was no significant change in the section capacity, irrespective <strong>of</strong> the differences in the densityand viscosity <strong>of</strong> diesel fuel and <strong>ethanol</strong>. This leads to a conclusion that the fuel injection pump doesnot need a separate section capacity adjustment when using <strong>ethanol</strong>. In order to compensate thedifference in the calorific value <strong>of</strong> the fuel compared to using diesel fuel in the engine, it is possible toincrease the section capacity. After the first ten-hour test cycle the capacity <strong>of</strong> the first and fourthsection was reduced by 6 cm 3 . The reduction <strong>of</strong> the section capacity was caused by the shifting thatoccurred between the case and control rack when running in the fuel injection pump. No significantreduction <strong>of</strong> the section capacity was observed in the course <strong>of</strong> further test cycles, as seen in Figure 3.By the end <strong>of</strong> the second test cycle (after 10 hours <strong>of</strong> operation) the capacity <strong>of</strong> the second sectionincreased by 2 cm 3 . During the fourth operating cycle (after 30 hours <strong>of</strong> operation) the capacities <strong>of</strong>the third and the first section were also increased. Based on the final measurements <strong>of</strong> injectionpressures we may conclude that the increase in capacity is caused by the reduction <strong>of</strong> the injectionpressure: I section – 28 bar; II section – 30 bar; III section – 40 bar; IV section – 20 bar.3·min-1Section capacity, cmI sectionII sectionIII sectionIV sectionWorking hours, hFig. 3. Section capacity <strong>of</strong> injection pump depending on test timeThe injection pressure in the fourth section was reduced the least, which is also characterised bythe stability <strong>of</strong> the capacity throughout the test. The section pressures in other sections were reducedmore than in the section four, but they remained within the standard limit and did not involvesignificant increase in capacity.Reduction <strong>of</strong> injection pressures was caused by the wear generated when running in the worksurfaces <strong>of</strong> the nozzle needles. The measurement <strong>of</strong> needle geometric circularity revealed the highestdeflection in case <strong>of</strong> the nozzle needle in the third section (see Figure 4). It follows that the reduction<strong>of</strong> the injection pressure in the third section was due to the increased deflection <strong>of</strong> shape, incomparison with other sections. According to a general tendency the shape deflections were reducedin the course <strong>of</strong> the test. But in case <strong>of</strong> the injector in the third section the deflection increased instead.257
ENGINEERING FOR RURAL DEVELOPMENT Jelgava, 26.-27.05.2011.Irrespective <strong>of</strong> that we may conclude that using <strong>ethanol</strong> does not cause ultrafast wear <strong>of</strong> the preciseunits <strong>of</strong> injectors.Fig. 4. Measurement results <strong>of</strong> geometric circularity <strong>of</strong> subsystem partsThe results <strong>of</strong> measuring the delivery valve retraction collar geometric circularity revealed thereduction <strong>of</strong> mean deflection in all sections. The reduction <strong>of</strong> deflections was caused by running in thedetails. We may conclude that the operation <strong>of</strong> the valves in <strong>ethanol</strong> environment during 100 workhours does not cause significant wear that would lead to major changes in the capacity <strong>of</strong> the fuelsupplyequipment. The same can be said to describe the wear <strong>of</strong> the plunger pairs. The greatest changein deflection, 1.667 µm, was found in the fourth plunger (Figure 4). The results gained from themeasurement <strong>of</strong> the hydraulic density <strong>of</strong> plunger pairs did not differ from the initial measurements,and the results corresponded to the factory requirements. Under the microscope one can see barelynoticeable scratches on the surface <strong>of</strong> the plunger. More visible scratches <strong>of</strong> the work surface,however, are seen on the delivery valve retraction collars (Figure 5), which, according to themeasurement results, did not change the hydraulic density according to the factory requirements.a b cdFig. 5. Work surface <strong>of</strong> subsystem: a – unloading collar before testing; b – unloading collar aftertesting; c – pump plunger before testing; d – pump plunger after testing.258
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impact of ethanol on fuel injection pump of diesel engine

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