Fuel systems associated with Gasoline Direct Injection (GDi) engines operate at pressures significantly higher than Port Fuel Injection (PFI) engine fuel systems. Because of these higher pressures, GDi fuel systems require a high pressure fuel pump in addition to the conventional fuel tank lift pump. Such pumps deliver fuel at high pressure to the injectors multiple times per engine cycle. With this extra hardware and repetitive pressurization events, vehicles equipped with GDi fuel systems typically emit higher levels of audible noise than those equipped with PFI fuel systems.
A common technique employed to cope with pump noise is to cover or encase the pump in an acoustic insulator, however this method does not address the root causes of the noise. To contend with the consumer complaint of GDi system noise, Delphi and Magneti Marelli have jointly developed a high pressure fuel pump with reduced audible output by concentrating on sources of noise generation within the pump itself.
This paper presents the development process of a low-noise GDi fuel pump. Typical vehicle Original Equipment Manufacturer (OEM) requirements and customer complaints are presented signifying the requirement for reduced noise. Internal sources of pump noise are discussed and solutions to reducing the noise from these sources are presented. Sound level measurements comparing the improved pump design with the baseline design and competitor pumps are shown. Implementing these solutions has helped produce a low-noise design and control strategies yielding a best-in-class high pressure fuel pump for passenger and light truck vehicles.