Patent Grant
7845623
The present invention relates to internal combustion engines and, more particularly, to carburetors and associated air intake components employed in internal combustion engines.
Small internal combustion engines are used in a wide variety of applications including for example, lawn mowers, lawn tractors, snow blowers and power machinery. Commonly, such internal combustion engines employ a carburetor to provide an appropriate air-fuel mixture to the combustion chamber of the internal combustion engine for generating power. Frequently, such carburetors have a fuel bowl that is coupled to a narrow throat/venturi region of the carburetor that serves as the air-fuel mixing chamber of the carburetor, and fuel enters the carburetor from the fuel bowl due at least in part to pressure differentials occurring within the venturi region.
Many such engines are used in seasonal machines (e.g., lawnmowers, snow blowers, tillers) or other machines that are not operated for long periods of time (e.g., chain saws), or that are operated under low-temperature conditions. When an engine is cold and/or has not be operated for a long period of time, it can be difficult to start the engine. Additionally, even after the engine has been started, the engine may not run smoothly until the engine warms up. To enhance the performance of such engines under these operational conditions, many engines include an engine priming mechanism by which, to achieve enhanced engine performance, the carburetor is provided with a richer air-fuel mixture.
To prime the carburetor, most carburetors in traditional schemes have a fitting that is pressed or screwed into the carburetor body. The fitting is further connected to passages leading to the fuel bowl attached to the carburetor, with the passages typically being cast or drilled into the carburetor body. Additionally, the primer fitting typically receives at its opposite end (opposite to the end that fits into the carburetor) a primer tube, which can either be directly connected to a primer bulb or lead to another location on the engine at which such a bulb or other priming device is located. More particularly, when a user presses the primer bulb, air is delivered from the priming bulb through the primer tube, the primer fitting and the passages within the carburetor body to the carburetor fuel bowl, and the resulting air pressure increase within the fuel bowl causes fuel to be driven into the carburetor venturi. Depending upon the embodiment, the priming bulb can provide a bowl vent (e.g., by including a small hole within the priming bulb) all by itself or in combination with additional passage(s).
Although adequate in many circumstances, such conventional priming mechanisms nevertheless are inadequate in some regards. In particular, such conventional priming mechanisms involving a primer fitting require assembly of the primer fitting to the carburetor body. As a result, the potential exists for the fitting to slip out of place or crack the carburetor body. Also, many conventional priming mechanisms are not well-suited for allowing engine operation under varying temperature conditions. For example, priming mechanisms utilized in engines that are designed for operation under warm (e.g., summer) conditions often are incompatible with optimal operation of the engines under cold (e.g., winter) conditions, since shielding that is often constructed around the carburetor of an engine to protect it from cold air and snow during operation under the latter conditions can obstruct access to the engine's priming mechanism.
For at least these reasons, therefore, it would be advantageous if an improved priming mechanism could be designed. More particularly, it would be advantageous if, in at least some embodiments, such an improved priming mechanism did not require or employ any separate primer fitting. Also, it would be advantageous if, in at least some embodiments, the priming mechanism was compatible with engine usage under various different temperature (or possibly other) operational conditions.
In at least some embodiments, the present invention relates to an air intake component. The air intake component includes a surface capable of being coupled at least indirectly to a carburetor assembly, where the surface includes first and second orifices, a first channel capable of communicating engine intake air from a first location to the first orifice of the surface, and a second channel by which at least one of the first location and a second location is connected to the second orifice. The second channel is capable of communicating at least one of a primer air pressure pulse from the at least one location to the second orifice and fuel fumes from the second orifice to the at least one location.
Further, in at least some embodiments, the present invention relates to a carburetor assembly. The carburetor assembly includes a carburetor wall defining an air-fuel mixing chamber, a fuel bowl, a passage linking the fuel bowl to the air-fuel mixing chamber, and an output port at a first end of the air-fuel mixing chamber, at which a mixture of air and fuel can be output. The carburetor assembly further includes a surface at a second end of the air-fuel mixing chamber, where the surface defines a first orifice that serves as an entry to the air-fuel mixing chamber by which engine intake air can enter the air-fuel mixing chamber. Also, the surface further defines a second orifice that is coupled to the fuel bowl by way of a further passage.
Additionally, in at least some embodiments, the present invention relates to an air intake assembly. The air intake assembly includes a first portion having a first surface, and a cover that is assembled to the first portion along a second surface. The first portion includes first and second channels linking a first region formed by the first portion and the cover to the first surface, and the first channel serves as a passage for engine intake air to be communicated to a carburetor, while the second channel serves to allow communication of at least one of a priming impulse and fuel vapors.
Further, in at least some embodiments, the present invention relates to a method of providing an air intake assembly. The method includes assembling an intake base in relation to a carburetor assembly, where the intake base includes first and second channels extending to first and second orifices along a surface of the intake base that interfaces at least indirectly the carburetor assembly. Upon the assembling of the intake base to the carburetor assembly, the first channel within the intake base is in communication with an air-fuel mixing chamber of the carburetor assembly by way of the first orifice and a second channel within the intake base is in communication with a fuel bowl of the carburetor assembly by way of the second orifice. Also, the method includes attaching a first cover to the intake base, wherein the first cover includes a priming bulb. Upon the attaching of the first cover to the intake base, the priming bulb is linked to the second channel so that, upon a compressing of the priming bulb, a primer air pressure pulse is supplied to the fuel bowl by way of the second channel and the second orifice.
Referring to
As shown particularly in
Additionally positioned along the upper plate 3 between the lips 4, 6, 8 and 10 are two concentric oval lips, namely, an outer lip 14 and an inner lip 16. Along at least a portion of its circumference, the outer lip 14 is formed by, and is merged with, certain of the lips 4-12 (particularly the lips 4 and 6). The inner lip 16 (particularly along about half of its circumference) defines an air filter cavity 17 that protrudes downwardly through the upper plate 3 farther into the intake base. The outer and inner lips 14, 16 also in particular are configured to interface an air filter (see
In addition, the upper plate 3 also shows several tubes. Among these is a base tube 18 extending upward through the air filter cavity 17, which is described in further detail below. Additionally, the upper plate 3 includes four summer intake tubes 20 positioned between the lips 10 and 12, each of which extends through the plate. As will be discussed in further detail below, when a summer intake cover is positioned onto the intake base 2, unfiltered air enters a cavity region formed by the intake base and the summer intake cover by way of the tubes 20. Notwithstanding the intake tubes 20 shown in
Referring to
The intake elbow 24 in particular is molded to include first and second channels 30 and 33, respectively (each of which is shown in phantom), by which the carburetor is in communication with the air filter cavity 17 when the carburetor is attached to the mounting face 26. The first channel 30 is connected to (and indeed comprises the inner channel within) the base tube 18 of
Turning to
Further as shown in
Generally speaking, during engine operation, air enters the air-fuel mixing chamber 46 from the air filter cavity 17 by way of the second channel 33, the second orifice 34 and the corresponding hole through the gasket 49. The venturi region 47 of the air-fuel mixing chamber 46 is at a sub-atmospheric pressure, while the fuel 61 within the fuel bowl 48 is at or close to atmospheric pressure, such that fuel is drawn from the fuel bowl 48 through the valve 50 into the venturi region 47. Upon entering the venturi region 47, the fuel is mixed with the air flowing therethrough, and the mixture then proceeds out of the carburetor body 44 and toward the cylinder(s) of the engine (not shown) with which the intake base 2 and carburetor assembly 42 are associated.
However, at times when the engine is cold or has not been operated for a long period (e.g., during or after the winter season when the temperatures outside are low), the engine is difficult to start initially. To enhance engine performance during such operational circumstances,
As shown in
Further as shown in
To provide a priming function, the winter intake cover 40 also includes a priming bulb 64 and an L-shaped priming tube 62 (typically a flexible tube) that extends horizontally inward into the intake cover away from the priming bulb and subsequently downward toward the base tube 18. A lower end of the L-shaped priming tube 62 (again typically a flexible tube) is linked to the base tube 18 when the winter intake cover 40 is attached to the upper plate 3 of the intake base 2, such that the priming bulb 64 therefore also is linked to the base tube 18. The priming bulb 64 can be a conventional flexible (e.g., rubberized) bulb that, upon being deformed, attempts to return to its normal bulbous shape. The priming tube 62 and the base tube 18 preferably are designed so that the tubes can be substantially sealed to one another when the winter intake cover 40 is attached to the upper plate 3, such that a substantially leak-free passageway is formed between the priming bulb and the fuel bowl 48 by way of the tube 52, the channel 30, the base tube 18 and the priming tube 62. Further, the priming bulb 64 has located thereon (e.g., within the middle of the outer surface of the bulb) a small opening/vent 65 via which air from the outside atmosphere can enter the priming bulb.
In alternate embodiments, the base tube 18 can be recessed (or formed as a recess within the floor of the intake base 2) in such a manner that the priming tube 62 can be press fit into a pocket (in which case the priming tube could be of a smaller diameter). Also, while in the present embodiment the priming bulb 64 is connected in a sealed manner to the first wall 66 of the winter intake cover 40 and the priming tube 62 extends from (or is formed entirely as part of) that wall, in other embodiments the priming bulb 64 and priming tube 62 can instead be connected to other walls of the winter intake cover or even mounted on the intake base 2 itself. Further, while in the present embodiment air from the outside atmosphere enters the priming bulb via the opening 65, in other embodiments air from the outside atmosphere can enter the priming bulb in a different manner, for example, by way of an additional channel formed within the winter intake cover 40. In some such embodiments, the priming bulb can be formed to include an internal lip or other formation that seals off of the additional channel when the bulb is pressed.
When the winter intake assembly 1 is employed, typically the engine is primed during (e.g., just prior to) the starting of the engine as follows. First, an operator covers the opening 65 on the priming bulb 64 (e.g., by covering the opening with his or her finger), thereby restricting air flow from the outside atmosphere into the priming bulb 64. Next, the operator depresses and compresses the priming bulb 64, such that air contained within the priming bulb 64 is forced through the priming tube 62 and into the fuel bowl 48 via the base tube 18, the channel 30 and the tube 52 (more particularly, air within the priming bulb and the respective tubes all moves toward the fuel bowl, and some of the air enters the fuel bowl, that is, a priming air pressure pulse is provided from the priming bulb to the fuel bowl). As a result, fuel within the fuel bowl 48 is forced upward through the valve 50 into the venturi region 47 of the carburetor body 44. Releasing of the priming bulb 64 by the operator allows air from the outside atmosphere to again enter the bulb, thus allowing the bulb to return to its original expanded shape without requiring air (or fuel) to be drawn out of the fuel bowl 48 toward the bulb.
In accordance with the present embodiment of the invention, the intake base 2 (and carburetor assembly 42) need not always be implemented in conjunction with the winter intake cover 40 as the winter intake assembly 1. Rather, as shown in
In contrast to the winter intake cover 40, the summer intake cover 80 only has first, second, third and fourth walls 83, 86, 88 and 90, respectively, that extend downward from a ceiling 89 to the lips 4, 6, 8 and 12 of the upper plate 3 of the intake base 2, and entirely lacks any further wall comparable to the wall 72 that extends downward to the lip 10 of the upper plate 3. It will be understood that, for clarity of presentation, a portion of the second wall 86 is cut-away in
Further in contrast to the winter intake cover 40, the summer intake cover 80 lacks any priming bulb or priming tube that can be attached to the base tube 18. No priming mechanism is needed (at least in the present configuration) since, during summer operation, the engine is typically capable of starting adequately without any priming boost (although in alternate embodiments, a priming bulb can be provided on the summer intake cover). Rather, in the present embodiment, the summer intake cover 80 is situated around and encloses an air filter 84 having a largely oval cross-sectional shape that is substantially concentric with respect to the lips 14 and 16 on the upper plate 3 of the intake base 2. More particularly as shown in
Additionally, when the air filter 84 is mounted onto the upper plate 3, the base tube 18 is located beneath the air filter 84 and is thus shielded from the outside atmosphere and from incoming unfiltered air by the air filter. In this arrangement, although the base tube 18 in combination with the tube 52 and the channel 30 does not serve as part of a priming mechanism, the base tube along with the tube 52 and the channel 30 can instead serve as a bowl vent for the fuel bowl 48. Due to the presence of this bowl vent, pressure changes within the fuel bowl 48 resulting from temperature changes or for other reasons can be accommodated without the injection of fuel into the air-fuel mixing chamber 46. Further, the air filter 84 acts to shield the base tube 18 from the unfiltered air entering the cavity 82, such that any air entering the fuel bowl via the base tube 18, tube 52 and channel 30 is filtered air. Additionally, because of the presence of the air filter 84, any fuel fumes escaping from the fuel bowl 50 via the tube 52, the channel 30 and the base tube 18 do not escape to the atmosphere but rather are contained (or substantially contained) by the air filter 84 (that is, the bowl vent is internal).
Thus, in operation, the summer intake tubes 20 located on the upper plate 3 of the intake base 2 draw in unfiltered air from the atmosphere. That air is then directed within the cavity 82 to the air filter 84, which cleans the air and passes the now-filtered air into the air cavity 17. The filtered air then further proceeds through the second channel 33 to the air-fuel mixing chamber 46 of the carburetor assembly 42. When the engine is not running, vapors from the fuel bowl are vented internally to the air filter cavity 17 beneath the air filter 84. Later, when the engine is running, the vapors (and their residue) captured by the air filter 84 proceed along with the filtered air to the air-fuel mixing chamber 46, and subsequently are consumed by the engine.
While the
Also, in some alternate embodiments, the priming mechanism of the winter configuration can be configured so that air entering the priming bulb 64 is not merely unfiltered air from the outside atmosphere but rather is filtered air. For example, one such embodiment can employ the air filter 84 not merely in the summer intake assembly but also in the winter intake assembly, and further such embodiment can additionally include first and second additional tubes within the winter intake cover and the intake base, respectively, that link the priming bulb to the region underneath the air filter. Further, it should also be mentioned that the use of positional/directional terms herein (e.g., an “upper” plate) is only for convenience and, although the use of such terms can serve as an indication of actual positions relative to the ground in certain embodiments, in other embodiments the positions/directions of the structures relative to the ground or any other reference point can take other forms.
It should be evident from the above description that at least some embodiments of the present invention are advantageous insofar as they allow for the integration of a priming mechanism with one or more air intake components of an engine. In at least some such embodiments, an air intake structure leading to the carburetor includes not only a passageway for communicating air to the engine, but also further includes an additional passageway that is capable of linking a priming bulb mounted on the air intake structure (or on an additional structure coupled to the air intake structure) to a channel within the carburetor leading to the fuel bowl. In such embodiments, the priming mechanism can be coupled to the fuel bowl without any primer fitting, and the presence of the priming mechanism allows for enhanced start up operation of the engine (for example, during wintertime operation), without tampering with or changing any parts of either the combustion engine or the carburetor.
Additionally, in at least some embodiments, the air intake structure can encompass multiple interchangeable portions, such that in some circumstances the additional passageway leads to a priming bulb mounted on the air intake structure, while in other circumstances the additional passageway only serves as a venting passageway to allow venting of fuel vapors from the fuel bowl to another location such as a cavity downstream of an air filter. Further, in at least some such embodiments, the air intake structure includes two (or possibly more) substitutable covers or other components allowing the air intake structure to take different forms suitable for different operating conditions, such as a first winter configuration and a second summer configuration. Thus, while in one form the air intake structure allows for priming of the engine, in another form the air intake structure allows for the fuel bowl to internally vent without changing the carburetor or the portion of the air intake structure that is coupled to the carburetor.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.
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