Gas and liquid contact apparatus – Fluid distribution – Valved
Reexamination Certificate
1999-02-16
2001-09-04
Chiesa, Richard L. (Department: 1724)
Gas and liquid contact apparatus
Fluid distribution
Valved
C261S079100, C261S081000, C261SDIG001, C261SDIG003, C261SDIG004
Reexamination Certificate
active
06283460
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fuel-air mixture apparatus, particularly for an internal combustion engine.
Fuel-air mixture apparatuses of the type where fuel is mixed with air prior to induction into the cylinder(s) of an engine generally rely on a pressure reduction at a throttle in the device to draw fuel into the device, in which case the device is known as a carburettor, or rely on fuel injection into the air as it passes through the device.
Generally, the prior devices rely on a single stage of mixture of fuel and air and are limited as regards the droplet size and total vaporisation of the fuel in the air which they induce. Inadequate vaporisation and too large a droplet size result in unburned and/or incompletely burnt fuel being present in the exhaust from the engine.
THE INVENTION
The object of the present invention is to provide a fuel-air mixture apparatus which causes low quantities of unburned and incompletely burnt fuel to be present in the exhaust.
The fuel-air mixture apparatus of my invention comprises:
a primary air passage having an inlet, an adjustable throttle and an outlet,
a secondary air passage having an inlet and an outlet to the primary air passage between its adjustable throttle and its outlet and
a nozzle for introducing fuel into the secondary air passage, whereby in use the fuel mixes with the air flowing through this passage prior to mixing with the air flowing in the primary air passage.
Whilst it can be envisaged that the nozzle should be a fixed orifice nozzle, it preferably has a variable orifice. In the preferred embodiments, the nozzle has a tapered needle in its mouth to provide variability by axial movement of the needle. In one embodiment, the needle has a small bead, preferably a small ball or invert cone, at its tip for inducing divergence of the fuel as it flows from the end of the needle and/or for discouraging fuel flow to the point of the needle and linear drop formation from the point.
Normally, the inlet of the primary air passage will be connected to an air cleaner and the outlet will be connected to an inlet manifold of an internal combustion engine.
The inlet of the secondary air passage can be from the primary air passage between its inlet and its throttle. Alternatively the inlets to the two air passages can be independent of each other, but normally downstream of the same air cleaner.
The outlet of the secondary air passage may be provided at a fixed throat in the primary air passage, to induce increased air flow speed in the primary passage and reduced pressure at the outlet of the secondary air passage for enhanced air flow in the secondary air passage. In one embodiment, a plurality of outlets from the secondary air passage are provided at the fixed throat. The secondary air passage has a branch surrounding the primary air passage, the said outlets being from tile branch and spaced around the primary air passage.
In one embodiment, the secondary air passage is provided with a constriction for inducing increased air flow speed therethrough and the nozzle is arranged at the constriction whereby the fuel is mixed with the air at its region of increased flow speed. The constriction can be formed as an annular space between the nozzle or the needle and a ring. Preferably the ring has up- and down-stream bevels meeting at an edge for inducing turbulence.
In another embodiment, the secondary air passage is provided with a chamber, with the nozzle being arranged to inject fuel into the chamber for initial fuel-air mixing in the chamber. The passage may have a constriction at the upstream and/or downstream ends of the chamber. When at the downstream end, the constriction can be at the outlet from the secondary air passage to the primary air passage.
The constriction(s) is/are preferably configured to induce turbulence in the air flow in the secondary air passage, to enhance the mixing of the fuel with the air, suitably by forming the constriction with a pair of bevels meeting at an edge.
Alternatively, or in addition to the constriction(s), the portion of the secondary air passage upstream of the chamber may approach the chamber at least substantially tangentially thereto, so as to induce swirling of the air flow in the chamber. In this embodiment, the nozzle is preferably arranged to introduce the fuel at the centre of the swirl, whence it can radiate for mixing with the air.
In one embodiment, the nozzle is so arranged that the fuel leaving its orifice impinges on an ultrasonic transducer for comminution of the fuel into small droplets.
In one embodiment, a linkage is provided for linking the needle to the adjustable throttle in the primary air passage for adjustment of the orifice of the nozzle, whereby the fuel flow from the nozzle is matched to the air flow in the two passages.
In another embodiment, a control device is provided for servo control of the nozzle orifice is in accordance with measurement(s) of throttle position and/or engine parameters including the composition of the exhaust from the engine, whereby the fuel flow from the nozzle is matched to the air flow in the two passages.
Whilst it can be envisaged that fuel flow from the nozzle may be induced by depressed pressure in the device at the nozzle's orifice; normally a pump will be provided for pumping fuel will be pumped to the nozzle. Preferably, the pump will be adapted to deliver fuel to the nozzle at substantially constant pressure.
It is envisaged that the fuel may be gaseous or liquid.
REFERENCES:
patent: 3640512 (1972-02-01), Morgenroth
patent: 3679186 (1972-07-01), Hideg
patent: 4216753 (1980-08-01), Inoue et al.
patent: 4224908 (1980-09-01), Bier et al.
patent: 5249773 (1993-10-01), Feld
patent: 2819474 (1978-11-01), None
patent: 850652 (1939-12-01), None
patent: 5672244 (1981-06-01), None
patent: 6001362 (1985-01-01), None
PCT Notice of Transmittal of the Interntational Search Report, Form PCT/ISA/220, Oct. 2, 1997.
Chiesa Richard L.
Sofer & Haroun LLP
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