Apparatus and method for lessening the accumulation of high boiling fraction from fuel in intake valves of combustion engines

An intake valve for a combustion engine having an oil reservoir and adapted for combusting fuel is disclosed. The intake valve includes a valve stem and a valve guide arranged proximate the valve stem. The valve guide and valve stem define a first clearance dimension and a second clearance dimension between an inner surface of the valve guide and an outer surface of the valve stem, wherein the second clearance dimension is greater than the first clearance dimension. The second clearance dimension is sized to accept a volume of oil quantified to dissolve high boiling fraction from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to an apparatus and method for lessening the accumulation of high boiling fraction from fuel in combustion engines, and particularly to an intake valve for a combustion engine configured to lessen the accumulation of the high boiling fraction at the intake valve.

A gasoline-fueled spark-ignition combustion engine traditionally has the fuel introduced into the intake system either through a carburetor or a port fuel injector. Some fuels contain high boiling materials, or fractions, such as polymer fuel additives or gum, and some of the high boiling fractions have a high viscosity, which generally increases exponentially with a decrease in temperature. Consequently, after an engine cools down, an accumulation of high viscosity high boiling fraction on the intake valve surfaces may result. Accordingly, there is a need in the art for an intake system in a combustion engine that may lessen the accumulation of high boiling fraction on intake valve surfaces.

SUMMARY OF THE INVENTION

In one embodiment, an intake valve for a combustion engine having an oil reservoir and adapted for combusting fuel is disclosed. The intake valve includes a valve stem and a valve guide arranged proximate the valve stem. The valve guide and valve stem define a first clearance dimension and a second clearance dimension between an inner surface of the valve guide and an outer surface of the valve stem, wherein the second clearance dimension is greater than the first clearance dimension. The second clearance dimension is sized to accept a volume of oil quantified to dissolve high boiling fraction from the fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.

In another embodiment, a valve guide for an intake valve of a combustion engine includes a surface for guiding a valve stem and a channel formed in the surface for receiving oil from an oil reservoir. The channel is sized to receive a volume of oil quantified to dissolve high boiling fraction from fuel to lessen the accumulation of high boiling fraction between the valve stem and the surface for guiding the valve stem.

In a further embodiment, a method for dissolving or diluting high boiling fraction from fuel at an intake valve stem of a combustion engine is disclosed. A volume of oil is passed from a first end of a valve guide toward a second end thereof through a first channel disposed between the valve stem and the valve guide, and the volume of oil is received at a second channel disposed at the second end of the valve guide. The volume of oil is quantified to dissolve high boiling fraction from fuel to lessen the accumulation of high boiling fraction between the valve stem and the valve guide.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention provides an intake valve for a combustion engine, the intake valve being structured to reduce the accumulation of high boiling fraction between a valve stem and a valve guide. While an embodiment described herein depicts a linear piston and cylinder arrangement as an exemplary combustion system for the combustion engine, it will be appreciated that the disclosed invention may also be applicable to other combustion systems, such as a rotary combustion system employed in a rotary combustion engine for example.

FIG. 1is an exemplary embodiment of a combustion system100for a combustion engine (not shown) having a cylinder105and a piston110defining a combustion chamber107, an intake port115, an exhaust port120, a fuel supply125, such as a fuel injector for example, an intake valve200, and an exhaust valve300. In an embodiment, intake valve200includes a valve stem205, and a valve head210(also referred to as a valve tulip) that has a seating surface212that seats against an intake valve seat117at intake port115during the opening and closing action of intake valve200. Surrounding valve stem205is a valve guide230that is dimensioned in close relationship with valve stem205for guiding the movement of valve stem205during the opening and closing action of intake valve200, best seen by referring toFIG. 2, which depicts an axial cross section view of an embodiment of valve stem205and valve guide230having exaggerated dimensions for clarity and discussion purposes. Referring briefly toFIG. 2, the clearance dimension g1between an inner surface232of valve guide230(diameter D2) and an outer surface207of valve stem205(diameter D1) is herein referred to as a first clearance dimension. Other dimensions depicted inFIG. 2will be discussed in more detail later. Referring back toFIG. 1, at the top of valve guide230is a valve seal235for controlling the flow of oil from an oil reservoir, generally depicted as130in the combustion engine, to clearance dimension g1between valve stem205and valve guide230, which assists in the control of oil consumption. The end208of valve stem205is arranged in mechanical communication with a valve cam (not shown) of the combustion engine for driving intake valve200to an open position. Intake valve200is driven to a closed position by the action of a valve spring215.

An exemplary operational cycle of combustion system100begins with intake valve200being closed, that is, with seating surface212seated against valve seat117, and fuel injector125providing a supply of fuel to intake port115where it is mixed with air. As depicted in the exemplary embodiment ofFIG. 1, the spray135of the fuel is directed toward valve stem205and valve tulip210. In response to intake valve200being opened via the valve cam, the fuel and air mixture is permitted to enter combustion chamber107, whereafter valve spring215drives intake valve200to the closed position and timed combustion and exhaust take place.

During the combustion cycle, outer surface207of valve stem205is at an elevated temperature, which results in the evaporation of the low boiling fraction of the fuel and the adhesion to outer surface207of the high boiling fraction of the fuel. With a portion of valve stem205moving in and out of valve guide230over many combustion cycles, some of the high boiling fraction on valve stem205may be pushed into clearance dimension g1between valve stem205and valve guide230.

Referring now toFIG. 2, the accumulation of the high boiling fraction (also referred to as residue or gum) at clearance dimension g1may be lessened by introducing a channel or groove240in valve guide230that is sized to accept a volume of oil, via oil reservoir130and valve seal235(FIG.1), quantified to dissolve the high boiling fraction. As used herein, the term dissolve is intended to convey any degree of dissolving or diluting of the fraction, and is not intended to imply a fraction that is 100% dissolved. In an embodiment, a preferred volume ratio of oil to high boiling fraction suitable for dissolving the high boiling fraction is equal to or less than about eight-to-one, with a more preferred volume ratio being equal to or less than about five-to-one, and an even more preferred volume ratio being equal to or less than about three-to-one. As depicted inFIG. 2, channel240may be trapezoid-shaped with tops and bottoms defined by diameters D2and D3, respectively, thereby defining a plurality of channels than run parallel to the central axis of valve stem205. However, channel240is not limited to a particular shape or number channels, but is rather configured appropriately for the function described herein. Diameters D1and D3define a clearance dimension g2, which is herein referred to as a second clearance dimension, and since clearance dimension g1, which is sized for valve clearance, is substantially smaller than clearance dimension g2, which is sized of dissolution of the high boiling fraction, the depth d of channels240is a substantial portion of clearance dimension g2. In an embodiment, clearance dimension g2is approximately five times clearance dimension g1. While the embodiment described herein depicts channel240on valve guide230, it will be appreciated that channel240may alternatively be applied to valve stem205.

Referring now toFIG. 3, a longitudinal cross section view of an alternative embodiment of valve stem205and valve guide230, having exaggerated dimensions for clarity and discussion purposes, is depicted. InFIG. 3, diameters D2and D3now define the depth d of channel250, which is a ring-like channel disposed proximate the end233of valve guide230. As with channel240, channel250is sized to accept a volume of oil, via oil reservoir130and valve seal235, quantified to dissolve the high boiling fraction. The width w and depth d of channel250are appropriately sized to provide the preferred 8:1, more preferred 5:1, or even more preferred 3:1, volume ratio of oil to high boiling fraction. In an embodiment, the dimension of clearance dimension g2, defined by diameters D1and D3, is about five times the dimension of clearance dimension g1. The embodiments ofFIGS. 2 and 3may be combined to provide a valve guide230with both trapezoid-shaped (or equivalently shaped, such as triangle-shaped for example) channels240′, as depicted by dashed lines inFIG. 3, and a ring-like channel250, with the diameter D5of channels240′ being equal to or other than diameter D3. In the combination embodiment, oil from oil reservoir130may flow to ring-like channel250via trapezoid-shaped channel240′, thereby placing the oil at a location close to where the high boiling fraction tends to accumulate.

In an alternative embodiment, and now referring toFIG. 4depicting a longitudinal cross section view of valve guide230, channels240may be replaced with channels260that are spiral-shaped around the inner surface232of valve guide230. In yet a further embodiment, channels240,250, and260, may be combined in any combination suitable for the purpose described herein.

In view of the foregoing, combustion system100, employing an embodiment of the invention, dissolves high boiling fraction from the combustible fuel by passing a volume of oil from oil reservoir130through valve seal235at a first end231of valve guide230, through a channel240′, to a channel250proximate a second end233of valve guide230. The volume of oil received at channel250is quantified to dissolve the high boiling fraction, thereby lessening the accumulation of high boiling fraction between valve stem205and valve guide230.

While an embodiment of the invention has been described employing a fuel injection system for supplying fuel, it will be appreciated that the scope of the invention is not so limited, and that the invention may also apply to a carburetor fuel delivery system.

As disclosed, some embodiments of the invention may include some of the following advantages: reduced accumulation of high boiling fraction on intake valve surfaces; reduced accumulation of high boiling fraction between the valve stem and valve guide; reduced surface contact area between moving parts, thereby reducing surface friction; and, increased lubrication between moving parts, thereby reducing system friction losses.