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The audible noise characteristics of direct injectors are important to OEM customers when selecting a high pressure gasoline fuel injector. The activation noise is an undesirable aspect that needs to be minimized through injector design, injector mounting, and acoustic treatments. Experimentally identifying the location and frequency of noise sources is beneficial to the improvement of injector designs. Acoustic holography is a useful tool in locating these noise sources by measuring a sound pressure field with multiple microphones and using this field to estimate the source location. For injector testing, the local boundary conditions of the noise source will affect the resultant sound field. Therefore, how the injector is mounted within the test fixture will change the resultant noise field measured. In this study, the process of qualifying an acoustic holography fixture using measurement system analysis for GDi fuel injector testing will be documented.

Compressed Natural Gas (CNG) is gaining popularity as a viable alternate transportation fuel in many regions of the world. Injectors capable of delivering pressurized gaseous fuels have been developed for this emerging vehicular market segment. CNG fuel injectors must be designed to be compatible and durable with a very low lubricity gaseous fuel to meet automotive OEM life expectancy standards. Traditional gasoline injectors utilize a “hard/hard” sealing configuration, in which both the valve and seat are constructed out of hard metals. When properly lubricated with liquid fuels, these valves can meet vehicular injector leak and flow durability requirements. However, metal valves operating without lubrication can experience excessive wear, which leads to unacceptable levels of gas leakage and flow shifts. The use of elastomer-to-metal sealing surfaces minimizes leakage, but may cause cold ambient operation challenges.

Delphi has developed a Continuously Variable Valve Lift [CVVL] mechanism to improve spark ignition engine part throttle fuel economy through the minimization of pumping losses and reduction of cam drive torque. The latest CVVL design is focused on meeting valve lift duration targets derived from combustion analysis at key speed and load points, reducing packaging envelope, and reducing part count for low cost. Delphi's CVVL design process, simulation used to predict performance, and hardware confirmation testing will be presented and discussed in this paper.

Fuel injectors capable of rapidly electrically heating ethanol for cold starts below ethanol's flash point temperature have been developed for the Brazilian transportation market. These injectors also enable the enleanment of 20°C cold start fueling, which has shown to reduce FTP bag emissions. Initial E-100 vehicular emission test results were published in SAE paper 2009-01-0615 and presented during the 2009 SAE Congress. Further development has shown that heated injector systems can enable emission reductions with a variety of automotive fuels. Engine control strategies which make use of heated injector systems, along with corresponding test results, are presented and discussed.

LEV-3 regulation changes require 100% SULEV30 fleet average by 2025. While present applications meeting SULEV30 are predominately small displacement 4-cylinder engines, LEV-3 standards will require larger displacement engines to also meet SULEV30. One concept previously investigated to reduce the cold start engine-out HC emissions was to heat the fuel injected during the cold start and initial engine idle period. Improved atomization and increased vaporization of heated fuel decreased wall wetting and unburned fuel. This resulted in more fuel available to take part in combustion, thus reducing the required injected fuel mass and HC emissions. Single cylinder engine testing with experimental heated Gasoline Direct Injection (GDi) injectors was conducted at 40°C engine coolant and oil temperature conditions. The operating mode simulated cold start idle operating conditions, with split injection for improved Catalyst Light-Off (CATLO) times.

Gasoline direct injection (GDi) fuel pumps use a plunger reciprocating in a sleeve to deliver pressurized fuel. Current industry-standard clearances between the plunger and sleeve create internal fuel leakage rates which are large enough to negatively affect pumping efficiency at low engine speeds. A polymer seal located between the plunger and sleeve has been developed to minimize the fuel leak solving the low engine speed efficiency problem. This paper will present analytical, experimental and validation testing results of improved pumping efficiency attained with this new seal. With the plunger seal, pumping efficiencies are shown to improve by a few percentage points at high engine rpms (erpm) but can double at low (cranking and idle) rpms, without degradation of performance after durability testing.

Ethanol is commonly employed as a transportation fuel in Brazil. However, since pure ethanol’s flash point is 12°C, flex-fuel vehicles marketed in Brazil are currently equipped with a redundant fuel system which delivers gasoline during cold starts below [typically] 18°C. Since these low temperatures are infrequently experienced in Brazil, gasoline in the auxiliary fuel tank may evaporate and/or varnish during extended dormant periods, resulting in poor quality or no-starts. It is therefore desirable to eliminate the gasoline system by vaporizing a sufficient quantity of ethanol to enable cold starts at low ambient temperatures. A port fuel injector capable of rapidly heating ethanol above its flash point has been developed which eliminates the need for the redundant fuel system. During cold-start conditions, the vehicle’s controller commands power to an electrical heater contained within each injector.

Innovative nozzle hole shapes for inwardly opening multi-hole gasoline direct injectors offer opportunities for improved mixture formation and particulate emissions reduction. Compared to increased fuel pressure, an alternative associated with higher system costs and increased pumping work, nozzle hole shaping simply requires changes to the injector nozzle shape and may have the potential to meet Euro 6 particulate regulations at today's 200 bar operating pressure. Using advanced laser drilling technology, injectors with non-round nozzle holes were built and tested on a single-cylinder engine with a centrally-mounted injector location. Particulate emissions were measured and coking deposits were imaged over time at several operating fuel pressures. This paper presents spray analysis and engine test results showing the potential benefits of alternative non-round nozzle holes in reducing particulate emissions and enhancing robustness to coking with various operating fuel pressures.

Brazilian ethanol vehicles are typically equipped with an auxiliary gasoline sub-tank fuel system which aids cold starting and drivability for low ambient temperatures. Port fuel injectors capable of rapidly heating ethanol have been developed to eliminate this auxiliary system. These injectors also enable reductions in emissions. Computational Fluid Dynamics (CFD) is used in conjunction with Taguchi Robust Engineering methods to optimize the heat exchanging geometry of these heated injectors. Simulation results are confirmed with experimental hardware and engine cold start testing. Modeling results, experimental hardware, and engine cold start performance is presented and discussed.