Patent Application
20060196481
The present specification, drawings and claims relate to fuel evaporative emission control in small internal combustion engines and particularly engines of less than about 50 horsepower (37.2 kilowatts) of the type used for e.g., applications in garden tractors, lawn mowers, generator sets and other portable appliances and marine applications.
Engine applications of the aforesaid type commonly have the fuel tank located proximate the engine for compactness. The fuel tanks employed in such applications usually have a user removable filler cap which contains a vent for permitting make-up air to enter the tank as the fuel is used by the engine. In such applications, the fuel feed is by gravity flow from the tank to the engine carburetor or in some applications by a small fuel pump. Furthermore, in such applications the engine is normally refueled in situ rather than at a refueling station; and, the fuel is poured into the tank from a portable container and quite often with the use of a user-supplied funnel or temporary pouring spout provided with the fuel container.
Recently, it has been mandated that fuel vapor from such small engine fuel systems not be permitted to escape to the atmosphere and that the fuel system including connections to the engine be sealed and prevent emission of fuel vapor to the atmosphere when the engine is not running; and, that when the engine is in operation the fuel vapor be drawn into the engine air inlet.
It is desired to provide for controlling emission in a small engine without requiring complete redesign of the fuel tank and fuel supply system for the small engine. In addition, it is desired to provide for controlling fuel vapor emission in a small engine in a manner which is low in cost and simple to incorporate in mass production of such engines and the appliances into which they are installed. It is further desired to facilitate the incorporation of vapor emission control for small engines with the fuel tank disposed proximate the engine without requiring redesign and retooling for the manufacturer of the tank and the associated components of the engine fuel system.
The present specification, drawing and claims describe a solution to the above-described problem where in one embodiment a separate tank structure defining a vapor space for allowing expansion of fuel vapor has integrally therewith a fuel vapor vent/rollover valve associated with the tank structure. The vapor space may have an outlet connected to the engine air inlet for effecting purging of the fuel vapor in the vapor space upon engine startup. In the aforesaid embodiment the tank structure is separate or remote from the fuel tank; and, in another embodiment a fuel vapor storage device such as an adsorbent filled canister is disposed in the line from the vent/rollover valve to the engine air inlet. In a further embodiment the tank structure defining the vapor space and the storage device containing the adsorbent are formed in a common housing. The vapor storage space may be connected either directly through the wall of the tank or through the fuel filler closure for receiving fuel vapor from the fuel tank.
Referring to
A fuel vapor conduit 24 has one end 22 connected through the upper wall of the tank to communicate with the interior thereof; and, the opposite end 26 of conduit 24 is connected to tank structure 28 defining a vapor space 30 which is disposed at a level above the fuel tank to function as a liquid surge tank in the event of sloshing or inversion of fuel tank 12. Tank 28 has a vent/rollover valve 32 associated therewith so as to have the inlet thereof receive vapor or liquid fuel from the space 30; and, the outlet thereof is connected to one end 34 of conduit 36, with the opposite end 38 of conduit 36 connected to the interior of a storage device or canister 40. Canister 40 may contain adsorbent 42 such as carbonaceous particulate material. The canister 40 has an atmospheric air inlet 44 and a vapor purge outlet 46 comprising one end of a conduit 48 which has its opposite end connected to the engine air inlet as denoted by reference numeral 50.
In the embodiment 10 of
Referring to
Tank 62 has one end 74 of a vapor vent line 76 connected through the upper wall of the tank for communicating with the interior thereof; and, the opposite end 78 of the conduit 76 is connected through fitting 77 to tank structure 78 which forms therein a vapor space 80.
The tank structure 78 may be formed in a common housing which also defines a separate vapor storage chamber 82. The vapor space 80 has associated therewith through the upper wall of the tank structure 78 a vapor vent/rollover valve 84 which has its inlet communicating with vapor space 80 and its outlet 86 connected to one end of a conduit 88 which has its opposite end 90 connected through the tank structure wall to storage space 82. If desired, a storage space 82 may contain an adsorbent 92 such as particulate carbonaceous material. The storage space 82 has one end 94 of a conduit 96 communicating therewith; and, the opposite end of the conduit 96 is connected to the engine air inlet denoted by reference numeral 98.
It will be understood that in the embodiment 60 of
Referring to
The vapor space 118 has associated therewith a vapor vent/rollover valve 124 which has its inlet receiving vapor from the space 118 and the outlet 126 thereof, connected to one end of a conduit 128 which has its opposite end 130 connected to communicate with the storage space 120 through the wall of housing 116. The embodiment 100 of
In the embodiment 100, the modular canister 116 is disposed at a level above the tank 102 such that if the fuel tank 102 is completely filled, liquid does not enter the vapor space 118. However, in the event of inversion of the tank 102, liquid entering the vapor space 118 is trapped therein by closure of the rollover protection functions of valve 124, description of which is omitted for the sake of brevity.
Referring to
A vapor conduit 152 has one end 154 connected through the upper wall of the tank 142, with the opposite end 156 connected through the wall of a surge tank 158 which defines therein vapor space 160 and which has a vapor vent/rollover valve 162 associated therewith and disposed through the upper wall thereof. The outlet 164 of valve 162 is connected to one end of a conduit 166 which has opposite end thereof connected to the engine air inlet as indicated by reference numeral 168. In the embodiment 140, surge tank 158 is located at an elevation above the tank 142 to prevent liquid fuel from entering the vapor space 160 when the tank is completely filled with fuel.
The various exemplary embodiments illustrated herein provide a simple and relatively low cost vapor emission control system for a small engine of the type having the tank mounted proximate the engine and with a user removable closure for the tank filler. The illustrated embodiments provide for a vapor expansion space and may include storage space filled with adsorbent material. The system retains vapor until the engine is operated whereupon the vapor is purged the engine air inlet.
Although certain embodiments have been hereinabove described and illustrated, it will be understood that modifications and variations may be made by those having ordinary skill in the art within the scope of the following claims.
