Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Patent
1997-06-24
1998-08-11
Miller, Carl S.
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
123458, 251205, 25112907, F02M 3302
Patent
active
057913188
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a valve for a metered introduction of fuel vapor evaporated from a fuel tank of an internal combustion engine into an intake tube of the engine. A valve of this kind has already been disclosed (European Patent 0 528 849), which is supplied with fuel vapor via an inflow fitting in order to be able to deliver this vapor into the intake tube in a metered fashion via an outflow fitting provided on the valve. The inflow fitting of the valve is connected, for example, via a hose to an adsorption filter, which temporarily stores the fuel vapor evaporated from the fuel tank. The valve is embodied so that it can be electromagnetically actuated and for this purpose, has a magnetic armature, which can be axially moved counter to the force of a valve spring by the magnetic forces of an electromagnet. When the electromagnet is without current, an end region of the armature, which is embodied as a valve closing member, is pressed against a valve seat in order to interrupt a flow connection from the inflow fitting to the outflow fitting. When current is supplied, the armature moves counter to the force of the valve spring and with its end region that is embodied as a valve closing member, lifts up from the valve seat, wherein a metering opening is unblocked at the outflow fitting so that a particular volume of fuel vapor can flow from the inflow fitting via the outflow fitting and into the intake tube.
The triggering of the electromagnet of the valve is carried out by means of a so-called pulse width modulated signal, which is composed of a pulse train of an electrical current that flows through the exciting coil of the electromagnet with a constant frequency. For triggering purposes, the pulse duration of the individual current pulses is increased or decreased by means of control electronics in order to thus obtain a continuously changeable attraction of the electromagnet to the armature. In the course of this, a particular axial position of the armature automatically adjusts itself as a function of the pulse duration of the individual pulses, in which position the armature pauses in order to deliver a particular volume of fuel vapor via the metering opening into the outflow fitting as a result of a throttling of the flow at the metering opening that is a function of the axial position of the valve closing member of the armature. The magnetic force of the electromagnet is a function of the pulse duration of the individual current pulses and is determined by the so-called pulse duty factor. The pulse duty factor indicates the quotient of the pulse duration divided by the pulse spacing (period duration) of the individual pulses. Due to friction effects and spring forces, the armature lifts up from its valve seat only after a particular pulse duty factor is reached, which is also called the opening pulse duty factor. Hysteresis effects result in the fact that the opening pulse duty factor can change with each renewed triggering so that a precise metering of extremely small volumes of fuel vapor has not been possible up to this point with a valve of this kind. Furthermore, the winding resistance of the exciting coil of the electromagnet is temperature dependent so that the opening pulse duty factor is also a function of temperature. It is therefore necessary to trigger the electromagnet by means of a current-regulated output stage, which prepares a pulse width modulated current signal. It is known, though, that a current-regulated output stage of this kind is relatively costly to produce in a vehicle that is equipped in the normal fashion with a direct current source.
The continuously functioning valve described delivers a flow of fuel vapor that increases in an essentially linear fashion with the rising pulse duty factor. However, the linear character of the valve described makes the metering of extremely small volumes of fuel vapor difficult when there is a relatively low pulse duty factor. In the prior art recited, the attempt is therefore made to compensate for this disadvantage by m
REFERENCES:
patent: 2764995 (1956-10-01), Krupp
patent: 3080885 (1963-03-01), Webster
patent: 4195814 (1980-04-01), Kimata
patent: 4471942 (1984-09-01), Kocanowski
patent: 4621604 (1986-11-01), Abthoff
patent: 4832312 (1989-05-01), Linder
patent: 5199404 (1993-04-01), Cook
patent: 5205537 (1993-04-01), Pfeiffer
patent: 5524593 (1996-06-01), Denne
patent: 5535725 (1996-07-01), Baker
Mallebrein Georg
Schulz Wolfgang
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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