Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
1999-10-29
2001-01-09
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S179170
Reexamination Certificate
active
06170473
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns a relief bypass device for a high-pressure direct-injection pump for feeding petrol to an injector manifold of an automobile vehicle internal combustion engine.
BACKGROUND OF THE INVENTION
Petrol engines for automobile vehicles currently being developed emit large quantities of carbon dioxide (CO
2
) into the atmosphere, at a rate of approximately 170 g of CO
2
per 100 km travelled, as well as other emissions.
To meet draft European anti-pollution standards that will come into force in 2005, automobile vehicle engines will have to operate in a way that reduces CO
2
emission by approximately 25%, i.e. to approximately 120 g.
The quantity of CO
2
emitted is directly proportional to the fuel consumption of the engine and the solutions adopted are therefore directed to reducing fuel consumption.
A first solution based on the concept of indirect sequential injection into an inlet manifold upstream of the inlet valves uses an impoverished air/petrol mixture. However, the results of this solution are limited in that a too poor mixture leads to incorrect engine operation.
A second solution, referred to as “direct-injection”, consists in placing injectors directly in a combustion chamber of the engine. According to this concept, on the one hand, the injector is subject to downstream pressure variations associated with the Beau de Rochas cycle and, on the other hand, the petrol injected must be metered very accurately. To this end, a high-pressure injection pump associated with a pressure regulator is used to supply fuel at high pressure to the injectors.
The high-pressure injection pump is a mechanical pump driven by the engine of the automobile vehicle. The rotation speed of the pump therefore depends on the engine speed.
The pressure regulator is therefore unable to assure a stable pressure at the injectors at particularly low engine speeds, for example during starting, which is prejudicial to good combustion.
An object of the present invention is to remedy the drawbacks referred to above by providing a device producing a stable petrol pressure at the injectors in order to reduce the fuel consumption and the level of CO
2
emission without degrading engine performance.
Another object of the invention is to reduce the residual petrol pressure in the injectors when the motor is stopped or if the electrical power supply to a vehicle engine control system is cut off.
SUMMARY OF THE INVENTION
To this end, the present invention consists in a relief device for a high-pressure direct-injection pump for feeding petrol to a manifold of injectors of an automobile vehicle internal combustion engine, the high-pressure pump being connected by a feed pipe to a low-pressure electrical fuel pump which communicates with a fuel tank and the high pressure delivered being regulated by a pressure regulator,
characterised in that the pressure regulator is a three-way regulator with three ports, a first port connecting the high-pressure pump to the manifold of the injectors, a second port connecting the high-pressure pump to the tank and a third port connecting the fuel pump to the manifold of the injectors, the second port being selectively open in normal operation, the first port being closed when the third port is open and vice versa in operation from an electrical power supply, the third port being:
normally open when the electrical fuel pump is not switched on, in which case the second port is forced open,
held open during the engine starting phase, the fuel pump being energised to supply petrol at a stable low pressure to the injectors, and
closed when the engine speed reaches a predetermined threshold corresponding to a rotation speed of the high-pressure pump adapted to supply petrol at a stable high pressure to the injectors.
The device in accordance with the invention can further include one or more of the following features:
the port B connects the high-pressure pump directly to the tank;
the port B is connected to the feed pipe downstream of the fuel pump;
the pressure delivered by the fuel pump is regulated by a low-pressure regulator;
the third port C is at least partly integrated into the three-way pressure regulator; and
the third port C is fully integrated into the three-way pressure regulator.
REFERENCES:
patent: 5207203 (1993-05-01), Wagner et al.
patent: 5558068 (1996-09-01), Akira et al.
patent: 5626121 (1997-05-01), Kushida et al.
patent: 6024064 (2000-02-01), Kato et al.
patent: 6065436 (2000-05-01), Koga et al.
patent: 33 15 927 (1983-11-01), None
patent: 195 39 885 (1996-11-01), None
patent: 0 643 219 (1995-03-01), None
Magneti Marelli France
Moulis Thomas N.
Piper Marbury Rudnick & Wolfe
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