The present invention relates to internal combustion engines and, more particularly, to evaporative emissions control systems and methods 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. It is common to find that such internal combustion engines employ a carburetor to provide an appropriate air/fuel mixture (also called “charge”) to the combustion chamber of the internal combustion chamber. Frequently, carburetors of such internal combustion engines are connected via a supply line to a fuel tank that store fuels such as gasoline, diesel fuel and other types of liquid fuels used by the engines. Typically, fuel enters the carburetor from the fuel tank at least in part due to pressure differentials between the fuel tank and the venturi region of the carburetor. The fuel is mixed with air within the venturi region of the carburetor.
When situated within a fuel tank, certain amounts of a liquid fuel typically become vaporized as hydrocarbons, particularly when temperatures within the tank rises, when the tanks experience high levels of jostling, and/or when the volume within the tank unoccupied by fuel (and filled with air) becomes rather large relative to the air space. The vaporization of fuel continues even during the normal course of storage of the fuel within the fuel tank.
Fuel vapors emanating from the fuel tanks of internal combustion engines are a main contributor to evaporative emissions from such engines. Such emissions from fuel tanks can occur particularly when passage(s) are formed that link the interior of the fuel tank with the outside atmosphere, for example, for venting purposes as well as when refueling occurs. Because fuel vapors can contribute to ozone and urban smog and otherwise negatively impact the environment, increasingly it is desired that these evaporative emissions from fuel tanks be entirely eliminated or at least reduced. In particular, legislation has recently been enacted (or is in the process of being enacted) in various jurisdictions such as California placing restrictions on the evaporative emissions of Small Off Road Engines (SORE), such as those employed in various small off-road vehicles and other small vehicles that are used to perform various functions in relation to the environment, for example, lawn mowers and snow blowers.
For at least these reasons, therefore, it would be advantageous if an improved system/device and/or method could be created to prevent or reduce evaporative emissions from fuel tanks, such as the fuel tanks of internal combustion engines including, for example, SORE engines.
In one aspect, the present invention relates to an evaporative emissions system for adjusting and/or controlling the purge flow rate of evaporative fuel vapors from a carbon canister in an internal combustion engine. The system includes an air intake assembly comprising an air filter, carburetor and an intake manifold in operational association with each other. The system also includes an evaporative emissions control device that is in fluid communication with the air intake assembly. The system further includes a fuel tank assembly in fluid communication with both, the evaporative emissions control device and the air intake assembly, and a housing that is capable of storing liquid fuels as well as an air space above the upper surface of the liquid fuel. The liquid fuel stored within the housing is additionally capable of evaporation producing fuel vapors comprising volatile organic compounds (VOC), which collect in the air space above the liquid fuel. The fuel vapors from the housing flow into the evaporative emissions control device and are subsequently purged into the internal combustion engine. In one embodiment, the purge rate of the fuel vapors can be regulated by a flow control device connected at least indirectly to the evaporative emissions control device and the air intake assembly. The flow control device further includes at least one of an orifice and a passageway, at least one of the orifice and the passageway sized in relation to the evaporative emissions control device and the fuel tank assembly.
In another aspect, a method for regulating purge flow rate into an internal combustion engine is disclosed. The method comprises providing an air intake assembly, an evaporative emissions control device and a fuel tank assembly in operational association with each other. A flow control device connected at least indirectly to the evaporative emissions control device and the air intake assembly is also provided. The method for regulating the purge flow rate can further comprise receiving fuel vapors at least indirectly from the fuel tank assembly into the evaporative emissions control device and purging the received fuel vapors into the internal combustion engine using the flow control device.
And in another aspect, the flow control device can comprise an orifice device, and more specifically, a connector device, having a channel section having a channel for receiving fuel vapors. Additionally, the channel terminates in at least one orifice to regulate purge flow rate.
In yet another aspect, the flow control device can comprise a filter device connected at least indirectly to the evaporative emissions control device and the air intake assembly. The filter device is used for cleaning the intake and/or purged air in addition to regulating the purge flow rate.
Other aspects and embodiments are contemplated and considered within the scope of the invention.
Embodiments of the invention are disclosed with reference to the accompanying drawings and these embodiments are provided for illustrative purposes only. The invention is not limited in its application to the details of construction or the arrangement of the components illustrated in the drawings. Rather, the invention is capable of other embodiments and/or of being practiced or carried out in other various ways. The drawings illustrate a best mode presently contemplated for carrying out the invention. Like reference numerals are used to indicate like components. In the drawings:
Referring to
Additionally, the evaporative emissions control system 2 includes an air intake assembly 4, a fuel tank assembly 6 and an evaporative emissions control device 8, each in operational association with one another. The air intake assembly 4 and the fuel tank assembly 6 are in fluid communication with the evaporative emissions control device 8 via a purge line 10 and a vapor line 12, respectively. The air intake assembly 4 conveys air from the outside atmosphere to the combustion chamber (not shown) of the engine for expansion and ignition. As air travels through the air intake assembly 4, air and fuel are mixed together to produce an air/fuel mixture, also called charge, which is delivered to the combustion chamber.
With reference still to
Although all the internal components of the carburetor 16 are not shown in
Disposed additionally downstream of the venturi region is a throttle value configured to control the flow of charge through the carburetor. The charge exiting the carburetor 16 enters the intake manifold 18 in a manner well known in the art. The intake manifold 18 then communicates the charge for ignition to the combustion chamber of the engine located downstream of the intake manifold (not shown).
The fuel tank assembly 6 includes a fuel tank 20 having a housing 21 and an input port 22. The shape and size of the fuel tank 20, as well as the material from which the housing 21 is constructed, can vary to convenience depending upon a number of factors, including: a) the internal combustion engine with which the fuel tank housing is used, b) the particular application for the engine, and c) the type of fuel that is stored or housed within the fuel tank housing. Typically, liquid fuel that is capable of evaporation at normal temperatures and pressures, such as gasoline, is stored within the fuel tank 20. In accordance with various embodiments of the invention, the fuel from the fuel tank 20 flows towards the carburetor 16 through an output port 24 via a fuel line 26. The fuel line 26 is coupled to the carburetor 16, typically to a fuel nozzle within the carburetor throat region (not shown). As a result, fuel is drawn into the venturi region from the fuel tank 20 through the fuel line 26. A fuel shut-off valve 25 can be present at the junction of the output port 24 and the fuel line 26. By virtue of the device (e.g., a fuel shut-off valve), the flow of fuel from the fuel tank 20 can be controlled. Optionally, a fuel filter 28 can be attached to the fuel line 26 for filtering dust and debris from the liquid fuel.
With reference still to
To minimize or possibly even completely eliminate the fuel vapors from being vented to the outside, the fuel tank 20 has formed thereon, or otherwise includes, a vent opening 32 (See
The evaporative emissions control device 8 of the present embodiment is typically a conventional canister or canister-type device (e.g., a carbon canister) that is in fluid communication with the air intake assembly 4 and the fuel tank assembly 6 and is also linked to the outside atmosphere. The evaporative emissions control device 8 in particular can be a separate stand-alone component coupled to the air filter 14, the carburetor 16, the intake manifold 18, or any other suitable component of the internal combustion engine. Alternatively, it is contemplated that the device 8 may be integrated into any of these or other components. The functionality of the evaporative emissions control device 8 is at least two-fold. First, the evaporative emissions control device 8 traps fuel vapors (i.e., containing a vaporized fuel component and the residual gases) from the fuel tank 20 to reduce evaporative emissions and purges those fuel vapors into the engine when the engine is running. Alternatively, when the engine is not running, the evaporative emissions control device 8 serves to trap the fuel vapors and recover the trapped fuel component from the fuel vapors for actively purging the recovered fuel into the engine and expelling any residual gases (e.g., air or fresh air) into the atmosphere. By virtue of the purging action of the evaporative emissions control device 8, as well as the expulsion of the residual gases (when the engine is not running), undesirable evaporative emissions, as well as fuel wastage, are both reduced.
For trapping and purging purposes, the evaporative emissions control device 8 includes a canister housing 34. The housing typically includes a chamber with a wall extending at least partially therein, and the wall provides a U-shaped cross-section of the chamber or interior of the canister housing. A plurality of ports (see
Adsorption of the fuel vapors within the evaporative emissions control device 8 is performed by way of an adsorbent media, such as, by way of example and not limitation, activated charcoal, or carbon pellets, located within the canister housing 34. Although, charcoal is a frequently used adsorbent media, other adsorbent media that are commonly available can potentially be used. The charcoal adsorbent material within the carbon canister is generally rated by its Normal Butane Capacity (NBC) measured in grams/milliliter. A typical NBC rating for such a media is 10 although carbon having other ratings is commercially available and can be used. In one embodiment, the evaporative emissions control device 8 includes only a single variety of the adsorbent material having a single evaporated adsorption fuel level (for e.g., the NBC rating). Nevertheless, in other embodiments, one or more additional or other types of adsorbent materials, each having different evaporated adsorption fuel levels, can be used.
One way of controlling evaporative emissions for SORE engines is by utilizing carbon canisters (of the kind described above) to trap the vented hydrocarbons from the fuel tank 20. The evaporative emissions control device sizes are typically determined based upon the volumetric capacity of the fuel tank 20 of the internal combustion engine. For example, a typical ratio of the quantity of liquid fuel within the fuel tank 20 to the adsorbent material within the canister housing 34 is 1.4 grams of hydrocarbon working capacity per liter of the size of the fuel tank 20 (1.4 g HC W.C./L fuel tank). However, the foregoing can be varied depending upon the NBC rating of the carbon used within the adsorbent media of the evaporative emissions control device 8. Generally, an internal combustion engine model can be used for a wide variety of applications requiring a variety of fuel tank sizes thereby resulting in a wide variety of designs and sizes of the evaporative emissions control device 8, all for achieving optimum purge flow rates.
Due to the various sizes and designs of the carbon canisters, the purge rate and concentration of hydrocarbons in the purge air can vary, resulting in varying engine performances. To prevent the engine performance from changing due to change in carbon canisters, it is often required that the carburetor be re-calibrated. Re-calibration of the carburetor can be an inconvenient, time consuming and a costly operation. Advantageously, the present invention provides flow control devices (discussed below) that are capable of controlling the purge flow rate without the requirement of re-calibrating the carburetor to obtain optimum engine performance, even while including varying carbon canisters (e.g., canisters of different sizes and designs).
Referring now to
The flow control device 40, and more specifically the orifice connector 41 shown, can typically be connected to the purge line 10 in a variety of ways. For example, the orifice connecter 41 can be connected by severing or otherwise disconnecting a small section of the purge line and connecting the orifice connector to the disconnected ends of the purge line. Alternatively, the respective line (e.g., the purge line) can be provided in a plurality (e.g., two) of portions and the portions connected together using the orifice connector. Various other connecting and engaging options and/or methods are contemplated and considered within the scope of the present invention. As shown, the orifice connecter 41 is a T-shaped (or substantially T-shaped) structure having first and second sections 42 and 44, respectively, connected together by way of a connection flange or flange-like section or a support section support member 43. Typically, the orifice connector 41 is made of molded plastic although other flexible or rigid materials or potentially even metals can be used. Additionally, the respective first and second sections 42 and 44 and the connection flange 43 may be formed as separate pieces coupled together in operational association or possibly as a unitary molded piece.
In general, the first section 42 of the orifice connector 41 includes a hollow cylindrical tube portion (or a channel section) 46 having first and second portions 45 and 47. In the present embodiment, the cylindrical tube 46 has smooth walls along its length and uniform dimensions. Further as shown in the present embodiment, portion 45 includes a barbed or barb-shaped portion 48, which serves as a receiving port for the fuel vapors coming from the evaporative emissions control device 8. Portion 47 has a regular circular contour and serves as an exit port for the fuel vapors flowing through the orifice connector 41 and headed towards the air intake assembly 4. It is contemplated that, in other embodiments, both portions 45 and 47 can potentially be extended to form barbed shaped portions.
Still referring to
The barbed or barb-shaped portion 48 further includes a frusto-conical portion 49 adjacent to the first portion 45 and a cylindrical portion 51 having an orifice 50 and extending from the frusto-conical portion. Fuel vapors from the evaporative emissions control device 8 enter the orifice connector 41 through the orifice 50 and exit through the second portion 47. The orifice 50 is in fluid communication with a channel or hollow portion (hidden from view) of the cylindrical tube 46. As such, a clear and unobstructed passage for air flow from the barbed shaped portion 48 of the first portion 45 to the second portion 47 through the orifice of the cylindrical tube is formed. The orifice 50 is typically placed directly in-line with the purge line 10 to prevent any loss as fuel vapors travel from the evaporative emissions control device 8 to the air intake assembly 4.
Additionally, the orifice 50 remains open at all times for regulating the purge flow rate of the evaporative emissions control device 8. Insofar as the orifice 50 remains open at all times, the orifice 50 does not employ a valve or a valve-like mechanism, which is capable of being opened and/or closed depending upon various conditions of the system within which the valve or the valve-like mechanism is employed. Furthermore, depending upon the size of the orifice 50, the amount of fuel vapors entering the orifice connector 41 can vary and be controlled. Therefore, by virtue of varying the orifice sizes as the sizes of the fuel tank 20 change, desired purge flow rates can be achieved. The variance of the purge flow rates with varying orifice sizes is shown in
Still referring to
Referring now to
Therefore, increase in the purging rate of the hydrocarbons with the increase in the orifice size effectively illustrates that the orifice connector 41 can be used to “calibrate” the purge rate of the evaporative emissions control device 8 into the engine. It is noted again that the orifice connector 41 is an exemplary orifice device provided in accordance with the first embodiment of the flow control device and in accordance with at least some aspects of the invention. Advantageously, by virtue of the orifice connector 41 controlling the purge flow rate of the hydrocarbons, the only component that needs to be changed to accommodate various shapes and sizes of evaporative emissions control devices and fuel tanks is the orifice connector 41 itself. Therefore, the orifice connector 41 provides an easy and cost efficient medium of maintaining the engine performance without changing or substituting system or engine components, such as changing or substituting evaporative emission control devices (e.g., canisters), which can be costly and time-consuming.
In general, the dimensions of the orifice connector 41 can vary to convenience. In the present embodiment, the orifice connector 41 has a length “L” that is approximately 43 mm long and a width “W” of approximately 20 mm, although orifice connectors having other dimensions can be used as well in other embodiments. In at least some alternate embodiments of the present invention, the orifice of the first embodiment of the flow control device (e.g., the orifice connector 41) can be sized to have a diameter of 0.060 inches for an evaporative emissions control device 8 sized for a 5 gallon fuel tank 20. In some other embodiments, the orifice can be sized to have diameters in the range of 0.005 inches to 0.500 inches. In alternate embodiments, orifices having diameters other than those mentioned above can be used as well.
The location of the orifice connector 41, on the purge line 10 for controlling the purge flow rates of the fuel vapors from the evaporative emissions control device 8 during the “purging” action can vary, thereby resulting in the orifice being positioned in various locations. For example, as shown in
Further still, as shown in
The evaporative emissions system 2 need not always be employed with the first embodiment of the flow control device 40, as described above. Rather, as shown in
In contrast to the first embodiment of the flow control device 40 used in the embodiments of
Further, the size of the air passages (or ports) 75 in the sintered shape can be varied by controlling the density of the compressed metal powder employed for making the sintered metal filter. Typically, as the density of the sintered filter 74 increases, the flow area through the air passages 75 decreases, thus restricting flow and controlling the purge flow rate. Additionally, as the cross section of the air passages 75 (e.g., having a cylindrical shape) in the flow direction decreases, the flow (e.g., the purge flow rate) is restricted. The geometry (e.g., length) of the sintered filter 74 additionally affects the purge flow rate, such that a longer filter typically restricts flow (and therefore controls the purge flow rate).
In particular, the size of the air passages 75 is typically determined in reaction to the evaporative emissions control device 8′ and the fuel tank assembly 6′. A typical metal that can be used for manufacturing the sintered metal filter of the present embodiment is bronze, although, other metals such as stainless steel, and non-metals such as glass, can potentially be used in other embodiments. Although an exemplary sintered metal filter that can be used in at least some embodiments of the present invention has been described above, in other embodiments, a wide variety of sintered filters that are commonly available and frequently used, can be used in other embodiments. In addition, the shape and size of the sintered filter 74 can vary depending upon the application, type of engine 3′ employing the sintered filter and location of the sintered filter within the evaporative emissions control system 2′.
As indicated above, the sintered filter 74 of the type employed in at least some embodiments of the present invention includes a plurality of air passages 75. The air passages 75 can be utilized for regulating the purge flow rate of the evaporative emissions control device 8′. Additionally, the air passages 75 of the sintered filter 74 remain open at all times during regulating the purge flow rate of the evaporative emissions control device 8′. In so far that the air passages 75 remain open at all times, the sintered filter 74 does not employ a valve or a valve-like mechanism that is capable of being opened and closed depending upon various conditions of the system employing the valve or the valve-like mechanism. By virtue of utilizing such a sintered filter having a plurality of air passages open during the regulating of the purge flow rate, various fuel tank sizes and various evaporative emissions control devices can be accommodated by only changing the sintered filter 74.
In addition to regulating the purge flow rate, the sintered filter 74 can be used for cleaning the intake air and/or the purge air. Particularly, during operation, the evaporative emissions control system 2′ receives additional air from the outside atmosphere for purging the fuel vapors from the evaporative emissions control device 8′ into the engine. Insofar that the purged air is routed to the air intake assembly 4′ of the engine 3′ when the engine is running, the sintered filter 74 can be used for filtering the purged air. By filtering the purged air, the sintered filter removes any residual dust and debris that can otherwise enter the air intake assembly 4′ thereby causing clogs and blockages, which can reduce engine performance. Therefore, in addition to regulating the purge flow rate, the sintered metal filter provides an additional advantage of cleaning the purged air. Relatedly, the sintered filter 74 can clean the intake air depending upon the placement of the sintered filter within the evaporative emissions control system 2′, as explained below.
Therefore, in accordance with at least some embodiments of the present invention, the sintered filter 74 can be provided for regulating the purge flow rate and cleaning the evaporative emissions in the evaporative emissions control system 2′. By virtue of having the sintered filter 74 having a plurality of air passages 75 formed therein by the process described above, the purged flow rate can be regulated. Additionally, the air sintered filter 74 can be used for cleaning the purged air.
Referring now to
As indicated above, the location of the second embodiment of the flow control device 40 (e.g., the sintered filter 74 filter device) within the evaporative emissions control system 2′ for controlling the purge flow rate of the fuel vapors from the evaporative emissions control device 8′ into the engine 3′ (See
The operation of the evaporative emissions control systems 2 and 2′ is explained below. In general, the operation of both evaporative emissions control systems 2 and 2′ employing the first embodiment of the flow control device 40 (e.g., the orifice connector 41) and the second embodiment of the flow control device (e.g., the sintered filter 74), respectively, is similar or substantially similar. For clarification purposes, the operation is explained with respect to the evaporative emissions control system 2, with the reference numerals of the corresponding components of the evaporative emissions control system 2′ given in parenthesis.
When the engine is not in operation fuel vapors including a fuel component and a hydrocarbon component collected above the liquid fuel within the fuel tank 20 (20′) pass through the vapor line 12 (12′) and into the evaporative emissions control device 8 (8′) at least in part due to pressure differentials. Thereafter, fuel vapors are adsorbed in the adsorbent material. By virtue of the fuel vapors being adsorbed and therefore trapped within the evaporative emissions control device 8 (8′), evaporative emissions, which in the absence of the evaporative emissions control device would have been emitted into the atmosphere, are trapped. At any instant when the engine is running and the internal pressure within the evaporative emissions control device 8 (8′) is higher than the internal pressure of the intake system (also referred herein as the air intake assembly 4) at the purge port location, the trapped fuel vapors can be purged into the engine. The purge rate of the trapped fuel vapors can be controlled by way of the flow control device (e.g., the orifice connector 41 and/or the sintered filter 74). Typically, the purging action involves drawing atmospheric air within the evaporative emissions control device 8 (8′) through the fresh air port. The air flow facilitates the purging action of the fuel vapors from the evaporative emissions device 8 (8′) to the engine whereby the fuel component from the fuel vapors is recovered. Alternatively, as the fuel tank 20 (20′) has cooled down due to non-use over extended periods of time or when the engine is not running, the pressure differentials within the evaporative emissions control device 8 (8′) and the fuel tank can cause the fuel component to be recovered from the adsorbent material and flow back to the fuel tank thereby reducing fuel wastage and reducing/eliminating evaporative emissions.
Notwithstanding the above-described embodiments, the present invention is intended to encompass a variety of other arrangements of orifice connectors and sintered filters within the evaporative emissions control system. For example, although the embodiments of
Additionally, the embodiments of the flow control device, as illustrated and previously noted, are exemplary in nature. Notwithstanding the various embodiments of the flow control device described above in relation to the orifice device (e.g., the orifice connector) and the filter device (e.g., the sintered filter), respectively, in at least some other embodiments of the present invention, the flow control device can be formed as a plug-like or a cork-like device (“plug/cork device”) having an orifice for regulating the purge flow rate. In embodiments employing such a plug/cork device having an orifice, the device can be positioned or otherwise placed within the purge line for regulating the purge flow rate. Additionally, the plug/cork device can be positioned within the purge line at one or more locations described above with respect to
Further, as already noted, the exact shapes and sizes of the orifice connector, fuel tanks, evaporative emissions control device and/or the various components of the air intake assembly can vary with a given embodiment. Relatedly, a plurality of sintered filters of varying shapes and sizes can be employed in the embodiments of
The present invention relates to a variety of embodiments of fuel tanks, evaporative emissions control devices, air intake assemblies and flow control devices as can be employed in a variety of applications and for a variety of purposes. For example, embodiments of the present invention can be employed in conjunction with a variety of different internal combustion engines used in vehicles, or for a variety of other purposes. Embodiments of the present invention can be particularly beneficial insofar as they reduce or even eliminate evaporative emissions from the fuel.
Also, it is contemplated that embodiments of the present invention are applicable to engines that have less than one liter in displacement, or engines that both have less than one liter in displacement and fit within the guidelines specified by the above-mentioned regulations. In still further embodiments, the present invention is intended to encompass other small engines, large spark ignition (LSI) engines, and/or other larger (mid-size or even large) engines. In additional embodiments, the present invention is intended to be used with containers or storage tanks other than fuel tanks holding volatile fluids, which are producers of volatile organic compounds (VOC) or evaporative emissions. In alternate embodiments, the present invention is contemplated for use with Electronic Fuel Injection (EFI) systems, in which the purged fuel vapors pass through an EFI throttle body of the engine.
Despite any method(s) being outlined in a step-by-step sequence, the completion of acts or steps in a particular chronological order is not mandatory. Further, modification, rearrangement, combination, reordering, or the like, of acts or steps is contemplated and considered within the scope of the description and claims.
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.
This application claims the benefit of U.S. provisional patent application No. 60/980,658 entitled “systems and methods for regulating purge flow rate in an internal combustion engine” filed on Oct. 17, 2007, which is hereby incorporated by reference herein.
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