Gasoline port fuel injection

Gasoline port fuel injection
  • Function
    Port fuel injection: tried-and-tested cost-effective technology
     

    In gasoline port fuel injection, the air-fuel mixture is created outside the combustion chamber, in the intake manifold. The injector injects the fuel in front of the intake valve. During the induction stroke, the mix flows through the open intake valve into the combustion chamber. The injectors are selected in such a way that the engine’s fuel requirements are covered at all times – even at full load and high speeds.

    Fuel supply

    The fuel supply module with integrated electric fuel pump, tank level sensor, and fuel filter conveys the required amount of fuel from the tank to the injectors at a defined pressure.

    Intake air adjustment

    Intake air adjustment ensures that the correct air mass is available for the engine at every operating point.

    Fuel injection

    In port fuel injection, the air-fuel mixture is prepared in the intake manifold and fed to the cylinder for combustion. The injectors mounted on the fuel rail constantly meter the required fuel volume into the air flow with great precision according to the spray design.

    Ignition

    Gasoline engines require an ignition spark in order to burn the air-fuel mixture in the engine cylinder. This spark is generated by a spark plug. The ignition coil provides the necessary high voltage, by transforming electrical energy from the battery into an ignition voltage and providing this voltage to the spark plug at the ignition point.

    Engine management

    Bosch's "Motronic" electronic engine control unit enables the prioritization and central control of all the various functions that a modern engine management system needs to fulfill. Taking torque as the key reference variable, the system efficiently adjusts the necessary air-fuel mixture.

    Exhaust gas treatment

    Exhaust gas treatment enables all international emissions standards to be met, e.g. using catalytic exhaust treatment. Oxygen sensing provides even more effective emissions control. The aim of this sensing mechanism is to always achieve a stoichiometric air-fuel ratio (λ=1).

     
  • Customer benefits
    The big hit with a big future
     

    Gasoline port fuel injection is the most widely used powertrain system for gasoline engines in the world. This proven technology still retains a great amount of potential to further reduce fuel consumption and emissions.

    When used in engines with a specific power of approx. 60 kW/liter and downsizing concepts of up to 25%, gasoline port fuel injection offers significant cost advantages over systems with high-pressure direct injection. As a low-pressure system (system pressure: approx. 6 bar), gasoline port fuel injection has a comparably straightforward operating strategy: simple injection control based on degrees of freedom with the injection time window. This does away with the complex requirements of high-pressure control (system pressure: approx. 150 bar) along with the high-pressure pump, the high-pressure sensor, the control system for the fuel-supply control valve, and the high-pressure injectors for multiple injections.

    Gasoline port fuel injection's robust combustion process tolerates even lower-quality fuels. Its reduced range of functions compared to systems with high-pressure direct injection allows simple software to be used, with a corresponding reduction in expenditure on system diagnostics.

    Bosch develops and manufactures innovative powertrain technology for vehicles with gasoline port fuel injection. Bosch's portfolio includes components for fuel supply, fuel injection, intake air adjustment, ignition, engine management, and exhaust gas treatment, which are available worldwide either individually or as part of coordinated systems.

     
  • Advanced PFI
    The cost-effective powertrain system is becoming even more energy efficient
     

    Advanced PFI is a Bosch system innovation for gasoline port fuel injection. Innovations such as pressure increase, twin injection, PFI scavenging, and open valve injection deliver impressive system benefits and redefine the technical possibilities of this propulsion principle. In combination with turbocharging, further reductions in fuel consumption and CO₂ emissions can be realized – with no impairment to torque or performance.

    Pressure increase

    To support air-fuel mixture formation during a cold start, the pressure in the fuel low-pressure system is raised temporarily to up to 6 bar. This increases the mass of the vaporizing fuel, reduces the spray droplet size SMD, and lessens manifold wall fuel condensation. As a result of the increase in pressure, the maximum volume of fuel that can be metered goes up, which supports injection synchronous with induction. The demand-driven provisioning of the amount of fuel and fuel pressure also reduces the average power draw of the fuel supply pump.

    Twin injection

    Using two injectors per intake port optimizes spray alignment and targeting in the cylinder, while spray targeting combines insights from the field of fluid physics with engine know-how. The spray geometries are modified optimally to the requirements of the specific intake port.

    Distributing the fuel through two injectors reduces the spray droplet size (SMD) thanks to a lower static flow rate, a lower spray density (due to the larger cone angle), and an optimized internal flow in the valve (single tapered spray). Overall, this improves vaporization, reduces manifold wall fuel condensation, and increases ignition stability. Further advantages include later ignition angles in cold-engine running and faster attainment of the catalytic converter's conversion point.

    PFI scavenging

    PFI scavenging is a technology developed by Bosch that is used in the turbocharging of downsized engines. During the period when both the intake and the exhaust valves are open, pure fresh air – without any fuel – is flushed through the combustion chamber. Fuel is injected only once the exhaust valve has closed. The injection period is set such that no unburned fuel leaves the combustion chamber.

    The scavenging effect achieves a higher exhaust gas flow rate even at low engine speeds, thereby shifting the operating point of the exhaust gas turbocharger to a lower so-called "base speed." The resulting increase in cylinder charge at low speeds improves the power output of gasoline port fuel injection engines specifically in the starting-off range.

    Open valve injection (OVI)

    What distinguishes this injection method is that fuel is injected into the incoming fresh air from the intake manifold only when the intake valve is open. This injection synchronous with induction occurs at low to medium speeds under engine full load and therefore in the knocking risk range. Thanks to the reduced wall contact of the air-fuel mixture, the fresh charge is cooled more effectively, reducing the knock tendency. As a result, the compression ratio of the basic engine can be increased by a factor of between 0.5 and 1.0 and fuel consumption falls in the part-load range. Using OVI in conjunction with twin injection enhances the OVI effect by means of improved atomization and vaporization and optimized targeting.

     
  • System benefits
    Advanced PFI: the economical, high-performance systems approach
     

    With Advanced PFI, Bosh has demonstrated that gasoline port fuel injection is becoming significantly more energy-efficient by means of innovative system development. Advanced PFI combines pressure increase, twin injection, PFI scavenging, and open valve injection.

    The use of Advanced PFI makes it possible to reduce fuel consumption by 12%, with a corresponding decrease in CO₂ emissions. The higher compression in the part-load range (OVI) alone accounts for 2% of the reduction. The remaining 10% come from downsizing with turbocharging and PFI scavenging.

    At the same time, Advanced PFI allows a reduction in HC emissions. Thanks to more homogenous air-fuel mixture formation and reduced manifold wall fuel condensation, HC emissions fall by 20% in the test cycle. Later ignition angles mean that the catalytic converter heats up faster.

    And last but not least, Advanced PFI also permits an increase in specific engine power output, with PFI scavenging achieving significantly higher low-end torque.

     
  • Automotive competence
    Comprehensive portfolio and extensive expertise

    With its comprehensive range of products and services, Bosch is a one-stop shop for vehicles with gasoline port fuel injection: from individual components all the way to integrated complete solutions for powertrain systems.

    The broad scope of Bosch's expert knowledge creates valuable synergies when collaborating with automakers to develop new components and systems.

    Systems competence and comprehensive know-how

    As a systems provider, Bosch knows the technical requirements, relationships, and dependencies involved in networking a gasoline port fuel injection powertrain system. From a technical perspective, the key criterion is the ability to apply and integrate powertrain technology exactly to the individual requirements of the vehicle or customer. This also improves cost effectiveness by reducing expenditure on development and tests and by bringing products to series production sooner.

    Driving innovation and technology

    Bosch’s big commitment to research and development produces a constant stream of powertrains with enhanced characteristics. Bosch innovations such as Advanced PFI with pressure increase, twin injection, PFI scavenging, and open valve injection enable reductions of up to 12% in fuel consumption and CO₂ emissions while optimizing the engine’s power output.

    Ensuring quality and reliability

    The high quality of Bosch products provides the basis for gasoline port fuel injection vehicles with state-of-the-art technology. Reliability and longevity are assured thanks to the Bosch system’s precision, durability, and service life designed for 240,000 km.

    Global presence

    With its gasoline port fuel injection development and manufacturing locations, Bosch has a global presence and is familiar with the specific requirements of individual markets. This proximity to automakers is unrivalled in the automotive components industry and makes for close, flexible collaboration. After all, short routes save time and money.

    Locations in Europe: Schwieberdingen (Germany), Bamberg (Germany), České Budĕjovice (Czech Republic)

    Locations in Asia: Saratov (Russia), Bangalore (India), Shanghai (China), Wuxi (China), Odawara (Japan), Yokohama (Japan)

    Locations in North America: Farmington Hills (USA), Charleston (USA),

    San Luis Potosí (Mexico)

    Locations in South America: Campinas (Brazil).

    Long-term partnership

    Bosch is a stable, reliable partner to automakers throughout the lifecycle of vehicles: from the design and development of powertrain technology for vehicles with gasoline port fuel injection all the way to series manufacturing. And beyond that to workshop diagnostics and spare parts supply. Having global logistics and large-scale series production on all continents ensures products can be shipped to customers quickly. Local contacts – whether in Bosch sales offices or resident engineers on automakers' premises – provide close customer support on an end-to-end basis.

     
     
 
 

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