Magnetically coupled fuel injector pump

Abstract

A pump (10) of high pressure direct injection fuel supply system is connected to the engine through a magnetic clutch which includes a motorizing function. The magnetic clutch comprises rotating electromagnetic cogs (20) attached to and driven by the engine and rotating permanent magnets (34) attached to and driving the pump. The slippage of the clutch is controlled by the on-off cycle of electrical power which is simultaneously supplied to all of the electromagnetic coils and may be responsive to the pressure in the fuel injections rail. The clutch may be op as an electrical motor by sequentially activating the electromagnetic coils for the purpose of providing fuel pressure even prior to rotation or cranking of the engine. An isolation barrier hermetically seals the fuel injection pump from the engine.

Description

BACKGROUND OF THE INVENTION [0001] A number of potential advantages have led the automotive industry to look with increasing interest toward utilizing common rail (manifold) high pressure direct injection for gasoline engines. A number of design constraints or difficulties seem to stand in the way of fully achieving the advantages. [0002] The pressurization of fuel to high levels (e.g., above 100 bar) requires considerable pumping power, which generates considerable heat. Moreover, the industry is looking for even higher rail pressures, above 200 bar. This heat could be dissipated to a large extent, if all the fuel that is pressurized, can be quickly injected into the engine cylinders. This is not possible, however, because the fuel pump flow rate is typically sized for engine cranking, which may be at 20-30 bar pressure at a high quantity discharge flow rate, whereas typical steady state cruising conditions require much lower quantity flow rates at 100 bar. Therefore, in a conventi...

AI Technical Summary

Benefits of technology

The system effectively regulates high-pressure rail pressure above 100 bar in response to engine demand, reducing energy imparted to discharged fuel and minimizing heat rejection, while maintaining high efficiency and reliability.

Problems solved by technology

A number of design constraints or difficulties seem to stand in the way of fully achieving the advantages.

The pressurization of fuel to high levels (e.g., above 100 bar) requires considerable pumping power, which generates considerable heat.

This is not possible, however, because the fuel pump flow rate is typically sized for engine cranking, which may be at 20-30 bar pressure at a high quantity discharge flow rate, whereas typical steady state cruising conditions require much lower quantity flow rates at 100 bar.

Although pre-metering and various spill control techniques can be used to some advantage in this regard, none of these techniques satisfactorily regulates the power output of the high pressure pump itself.

Another difficulty is encountered with high pressure pumps that are driven directly by the engine (e.g., crank shaft, cam shaft, accessory belt).

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