US 3352294 A
Description (OCR text may contain errors)
Nov. 14, 1967 w. F. BILLER ETAL 3,352,294
PROCESS AND DEVICE FOR PREVENTING EVAPORATION LOSS Filed July 28, 1965 AIR CLEANER CARBURETOR MAKE MANIFOLD FIGURE I 4 Sheets-Sheet 1 ACTIVATED CARBON BEDS 4 FUEL TANK l FUEL PUMP WILLIAM F. BILLER CHARLES W. SKARSTROM PATENT ATTORNEY INVENTORS Nov. 14, 1967 w. F. BILLER ETAL 3,352,294
PROCESS AND DEVICE FOR PREVENTING EVAPORATION LOSS Filed July 28, 1965 4 Sheets-Sheet 2 ACTIVATED CARBON BED AIR CLEAN-ER CARBURETOR |25 ORIFICE I24 c I22 INTAKE MANIFOLD AMhUvAAAlavuvuuuuluuauuM u m FIGURE 2 l l FUEL TANK I04 I FUEL PUMP WILLIAM F. BILLER CHARLES W. SKARSTROM PATENT ATTORNEY INVENTORS Nov. 14, 1967 Filed July 28, 1965 FUEL, GRAMS FUEL, GRAMS w. F. BILLER ETAL 3,352,294
PROCESS AND DEVICE FOR PREVENTING EVAPORATION LOSS 4 Sheets-Sheet 5 IN ALL RUNS (CHARTS LE6 BI AMOUNT OF PURGE WAS ABOUT I0 30 CUBIC FEET OF AIR PER PURGE. AVERAGE CUBIC FEET.
CHART I I I I I I I I GAS TANK CANISTER: l Gul. Cup.
GAS TANK: 22 Gal. Cup.- Full 60F. Io I0OF. 9.0 RVP Fuel I962 Cur 'After Adsorbtion Alternate Runs I I I I I I I 0 5 I0 l5 2O 25 4O 5O RUN NUMBER CHART 2 I I I CARBURETOR CARBURETOR CANISTER: lOt. Cup.
CARBURETOR BOWL: F to lF. No Purge Purge After Each Hot Souk 5o After Adsorbtion After Purge Guard CunisIer RUN NUMBER PATENT ATTORNEY INVENTORS Nov. 14, 1967 w. F. BILLER TAL 3,352,294
PROCESS AND DEVICE FOR PREVENTING EVAPORATION LOSS 4 Sheets-Sheet 4 Filed July 28, 1965 mmmsaz zam 8 Q moOQ 2 meow 50m mokumammzo 5 5m 8.2.2 6. EQzS mofi mm INVENTORS WILLIAM F. BILLER CHARLES W. SKARSTROM m wuj cimp PATENT ATTORNEY United States Patent ABSTRACT OF THE DISCLOSURE Apparatus comprises a closed system for containing and subsequently consuming vapors normally escaping to the atmosphere from an internal combustion engine utilizing a pair of absorbent beds. The respective absorbent beds are interconnected by suitable conduits and control means to the fuel supply bowl associated with a carburetor and the fuel supply tank.
The present invention is broadly concerned with an improved method of operating an internal combustion engine wherein fuel vapors are prevented from venting into and polluting the atmosphere. The invention is also concerned with an improved apparatus or device for attaining this result. A more specific adaptation of the invention is a method of operating the internal combustion engine wherein fuel constituents normally lost to the atmosphere are combusted in the engine to secure greater mileage. In essence, the method and apparatus of the present invention utilize at least one adsorbent bed to adsorb vaporized fuel constituents and then desorbs these fuel constituents and combusts the same in the engine.
It is well known that air pollution presents health, nuisance, and economic problems, and that the fumes, vapors, and gases evolved from internal combustion motor vehicles contribute significantly to air contamination. It is also known that generally these fumes and vapors are emitted into the atmosphere from the motor vehicle as exhaust gases discharged through the tailpipe, or are due to unburned fuel constituents which are emitted through the vent in the fuel storage tank and through cuts from the carburetor bowl. For example, it has been estimated that from about to 20% by volume as, for example, about by volume of the total vapors and fumes emitted unburned to the atmosphere from an internal combustion motor vehicle are evaporated from the gasoline tank and the carburetor bowl.
Air pollution control authorities in California have considered these sources of great enough significance to require control. As a result California has adopted emission standards calling for approximately an 80% reduction in evaporation losses from carburetors and fuel tanks. The present invention is particularly concerned with the elimination of fuel losses from the vehicle fuel tank and carburetor bowl and with their ultimate use in the combustion chamber. In accordance with the present invention fuel vapors, such as hydrocarbon fuel vapors, alcohol vapors and the like, which are emitted either from the fuel reservoir or the carburetor bowl, are adsorbed on an adsorbent and thereafter desorbed and combusted in the engine.
The losses from the fuel reservoir tank are caused by factors which include the rising temperature of the fuel as the vehicle is operated and rising atmospheric temperatures which cause the reservoir or fuel tank to reathe through the vent, or vents, in the fuel tank thereby emitting unburned fuel constituents into the atmos phere. In many instances the temperature of the fuel reservoir may be from about to F. higher than the atmospheric or ambient temperature.
Furthermore, after the engine has been operated for a period of time and then turned olf, the temperature of the fuel in the carburetor bowl rises as heat flows to the carburetor from the hot engine. The fuel is said to undergo a hot soak. Data have shown that the temperature of the fuel in the carburetor bowl can rise to as high as about 200 F. after the hot engine has been turned off. It has been estimated that the loss per hour from a gasoline tank may range from about 2 to grams per day and that the hot soak loss from the carburetor bowl may range from about 2 to 50 grams per hot soak.
Thus, in accordance with the present invention as hereinbefore mentioned, these fuel vapors are adsorbed on an adsorbent and then desorbed and combusted in the internal combustion engine. The process and apparatus of the present invention may be more fully understood by reference to the drawings illustrating embodiments of the same. FIGURE 1 illustrates the use of two adsorbent beds while FIGURE 2 illustrates an adaptation using a single bed.
Referring specifically to FIGURE 1, fuel tank or fuel reservoir 10, has a vapor space 1 and a fuel layer 2. Fuel tank 10 contains a conventional cap 3 permitting fuel to be introduced into the tank 10. Fuel cap 3 also contains a conventional vent which normally permits the tank to breathe whereby expanding vapors are emitted into the atmosphere. The vent on the tank 10 may be placed in other positions. In accordance with one conventional method liquid fuel is withdrawn from reservoir 10 by means of line 5, fuel pump 6 and introduced into carburetor bowl 20 by means of line 7. A conventional float, or equivalent means (not shown) positioned in carburetor bowl 20, controls the level of the liquid fuel in the carburetor bowl. Carburetor bowl 2%) is normally supplied with a vent 11, which permits vapors to pass into the atmosphere.
In accordance with conventional operation atmospheric air is introduced by means of line, or conduit, 12 and passes through an air filter 30. The air passes downwardly through the carburetor wherein fuel is Withdrawn from bowl 20 by means of line 8 and passed into a carburetion means 9 where the same is mixed with the incoming air. A choke element 31 is positioned normally ahead of the carburetion means 9. A flapper valve or element 14 controls the introduction of the fuel-air mixture into the intake manifold 40 which element distributes the fuelair mixture into the respective cylinders.
As pointed out heretofore, due to temperature variations and fuel tank breathing, fuel vapors pass from the tank 10 through the vent 4 and are lost into the atmosphere thereby causing contamination of the atmosphere. Also as pointed out heretofore, after the engine has been run for a time period the entire engine block is very hot and when the engine is turned off, the fuel in the carburetor bowl becomes quite warm reaching temperatures as high as F. and greater. This causes a portion of the fuel to be vaporized. The vapors are vented through vent 11 and further contaminate the atmosphere. Also, in addition, valuable fuel constituents are lost rather than combusted in the engine.
In accordance with the present invention, vents 4 and 11 and any other open vents which would allow loss of vapors from the fuel system to the atmosphere are closed off. A conduit 15 is atfixed to the fuel tank to provide communication to one end of an adsorption zone 50. Adsorption zone 50 contains a suitable adsorbent 17 for adsorbing vaporous fuel constituents. A vent 16 is provided at the other end of adsorption zone 50 which provides communication to the atmosphere.
The quantity of adsorbent 17 provided is sufficient to adsorb all vaporous fuel constituents emitted from tank 3 and to prevent any breakthrough of these constituents through vent 16.
The quantity of adsorbent required will be a function, among other factors, of the. particular engine design, environmental conditions and particular adsorbentor adsorbent mixture utilized. The adsorbent used in the descriptionof the drawing is activated carbon.
A conduit or line 18 communicates. with conduit intermediate fuel tank 10 and adsorption zone 50. This conduit preferably has an adjustment valve, or equivalent means, 19,so as to control the flow of vapors into a conduit 21 which communicates with intake manifold 4-0.
Thus, when the fuel in tank 10 emits vapors due to temperature rise, change in pressure, etc., and when the engine is not operating these vapors are adsorbed on the adsorbent in adsorption zone 50. When the engine is operating, the suction pressure or vacuum in manifold 40 not only will draw atmospheric air into air filter zone 30 but also will draw air in through vent 16, conduit 18; through conduit 21 into manifold 40. This will backwash or backfiow air through adsorption zone 50 from the other end to the one end in a manner to desorb the fuel constituents which were adsorbed previously on the adsorbent. As pointed out heretofore, the amount of adsorbent provided is sufficient so that when fuel constituents are being adsorbed none of these fuel constituents will pass into the atmosphere by meansof line or vent 16. The amount of backwash air passed through vent 16 controlled by valve 19 or equivalent means, is sufficient to desorb the previously adsorbed fuel constituents.
Referring to the carburetor bowl 20 when the engine is turned off after running, fuel constituents will vaporize and flow through line 22 into one end of a second adsorption bed 60 which is provided with an adsorbent which will adsorb the vaporized fuel constituents. Here again, sufiicient adsorbent is provided so as to prevent any breakthrough of the fuel constituents into line or conduit 23 provided near the top or at the other end of zone 60. This conduit 23 preferably communicates into air filter zone 30, although it may be vented'directly into the atmosphere by means of line 32 controlled by valve 33.
A conduit 24 communicates with conduit 22 intermediate zone 20 and the one end of zone 60. Conduit 24 also communicates with conduit 21 which communicates with the intake manifold 40. Thus, when the engine is operating,air flows from zone 30 through conduit 23 into the other end of zone 60 and backwashes through zone 60 so as to desorb the constituents previously adsorbed on the adsorbent. The desorbed constituents pass out of the one end of zone 60 and into the manifold 40 by means of conduits 24 and 21. A limiting orifice or equivalent means 25 may be provided to control the rate of flow and to balance the pressure drop as compared with the pressure drop across the flapper valve 14. The amount of air backwashed by means of line 23, is sufficient to desorb the fuel constituents previously adsorbed in zone 60.
Referring specifically to FIGURE 2, utilizing a single adsorbent bed, vaporized fuel constituents from fuel tank 100 are passed through line 101 and absorbed in zone 110 containing a suitable adsorbent 102. Liquid fuel is passed to the carburetor cup 120 by means of line 103, pump 104 and line 105. Vaporized constituents from the carburetor cup are passed into the lower or one end of zone 110 by means of line 106. Air is passed through filter zone 130 and into carburetion zone 121 where it is mixed with liquid fuel introduced from the carburetor cup. A flapper valve 122 controls the amount of air-fuel mixture introduced into intake manifold 140.
When the engine is operating a portion of the incoming air is passed through line 123 and enters the other end of zone 110 and backwashes through the adsorbent, thereby desorbing fuel constituents. The amount of air backwashing is sufficient to desorb the adsorbed constituents and is controlled by check valve or previously equivalent means 124. The backwashing air containing desorbed fuel constituents passes through line 125, through check valve 124 and is introduced into the intake manifold. The structure and method described ,with respect to FIGURE 2 is substantially the same as that described with respect to FIGURE 1 except that a single adsorbent bed is utilized.
The present invention may be more readily understood by the following examples illustrating adaptations of the same.
Example 1 Full scale operations in accordance with the present technique were conducted utilizing a 1962 Chevrolet automobile fitted with activated carbon breather canisters. The car was mounted on a dynamometer in a temperature controlled room. One canisterwas in communication with the gasoline fuel tank while the second canister was in communication as described with the carburetor bowl. All vents except through the canisters were closed; At the start of the engine operation, the room temperature, the gas tank and the carburetor bowl were at 60 F. The room temperature was gradually raised to F. with the car running at 30 mph with a road load. When the fuel in the gas tank reached F. in 60 to 80 minutes, the engine was stopped. During the hot soak the carburetor bowl reached a maximum temperature of 175. to F. The ambient room temperature was kept at 90 F. during the 60 minute, hot soak. Thus, in these tests, the engine was run for a period of 60 to 80 minutes and then turned off for a period of 60 minutes. After the hot soak, all temperatures were brought back to 60' F. Approximately 50 such runs were made.
The canister in communication with the fuel tank contained one gallon of activated carbon while the canister in communication with the carburetor cup contained about one quart of activated carbon.
No backwash was utilized to desorb adsorbed constituents until the respective canisters were saturated with fuel constituents and breakthrough of the fuel constituents occurred.
The results of these tests are illustrated in Chart 1 and Chart 2.
It is to be noted that with respect to Chart 1, 35 runs occurred before the activated carbon became saturated, containing about 380 grams of adsorbed hydrocarbons. When breakthrough occurred at this point the system was run as described with respect to the present invention whereby while the engine was running, backwash of atmospheric air was secured. It is to be noted that the amount of adsorbed constituents dropped to about 310 grams during engine operation and then picked up about 22 grams during nonengine operation. After about 50 runs, the amount of fuel after purge on the adsorbent was about 240 grams and when not running, about 252 grams. No fuel break-through occurred from the time backwashing began.
With respect to Chart 1 for experimental reasons purge or backwashing was carried out every other cycle. If backwashing had been carried out every cycle, then the pickup of fuel on the adsorbent would approximate about 5 grams each cycle. This is due to the fact that evaporation occurs from the tank while the engine is running and if backwashing is carried out this evaporation from the tank passes directly into the intake manifold together with desorbed constituents. If backwashing is not carried out while the engine is running, the evaporation from the tank which occurs while the engine is running passes into the adsorbent bed and is adsorbed thereon.
With respect to Chart 2, the canister is associated with curred to the atmosphere. The under-hood temperatures range up to about 160 F. during the hot soak.
Example 2 TAB LE I Run Number Weight of 1 Qt. Silica Gel Bed After Purge After Hot Soak Grams Grams 1, 198 1, 204 1, 198 1, 208 1, 197 1, 205 1, 197 1, 203 1, 199 1, 207 1, 198 1, 208 1, 198 1, 207 1, 199 1, 208 1, 199 1, 206
In the foregoing operation, an activated carbon guard adsorbent bed was positioned after the silica gel bed. This guard bed did not pick up any weight indicating that no losses were occurring through the silica gel bed and that this silica gel bed had attained steady state conditions.
Example 3 In another operation, similar to that described with respect to the foregoing examples, activated alumina was used as the adsorbent. No backwashing was employed until about the th run. During this period, approximately 24 grams of fuel was adsorbed. Backwashing was then employed with the result that the Weight of the adsorbent dropped below its original weight. This is due to the fact that water was being desorbed from the activated alumina. (See Chart 3).
It is apparent that steady state conditions were attained at about the th run wherein during the adsorption cycle, about 12 grams of fuel was picked up, which was desorbed on the backwashing cycle. It is to be noted that the guard canister of activated carbon did not gain any weight which indicated no leakage through the activated aluminum bed.
Example 4 Other operations were conducted as described wherein the activated carbon was saturated with Water prior to the adsorption and backwashing cycle. No adverse results Were secured when the activated carbon was saturated with water which indicates that the system will function in high humidity and fog conditions.
The present invention is adapted to provide and prevent contamination of the atmosphere when using any fuel utilized in an internal combustion engine. The fuels may be, for example, gasoline, diesel fuel or any type fuel containing hydrocarbons, alcohols, or other combustible liquid substances or mixtures.
The adsorbent may be any one which is adapted for adsorbing the vapor constituents of these fuels. Suitable adsorbents are, for example, activated carbon, silica gel, molecular sieves and activated alumina.
The amount of backwash or backflow required will be a function of the particular fuel used, the particular adsorbent used, the quantity of adsorbent used and temperature and pressure conditions.
In its broadest adaptation, the present invention covers the method of operating an engine wherein vaporous constituents of a fuel are adsorbed on an adsorbent and thereafter desorbed from said adsorbent and introduced into an internal combustion engine. The preferred adaptations are to adsorb vaporous constituents from liquid fuel reservoirs which are ahead of the carburetor and to adsorb these vaporous constituents on an adsorbent. These vaporous constituents are then desorbed by backflowing or backwashing atmospheric air by the action of the engine and then are introduced as an enriched fuel-air mixture into the engine. The apparatus features, in essence, comprise the utilization of a parallel airstream structure wherein the first airstream is a conventional one flowing through the carburetion Zone and into the manifold while the second stream backflows through a bed of adsorbent to remove therefrom vaporous constituents of the fuel previously adsorbed thereon, which second airstream is then introduced into the manifold. This second stream will also contain vapors emitted from the fuel tank and carburetor bowl during engine operation. One preferred adaptation of the present invention is for use with an internal combustion engine wherein the fuel is a hydrocarbon fuel such as a gasoline and where the adsorbent is activated carbon.
What is claimed is:
1. In a system for containing and subsequently consuming the vapors normally escaping to the atmosphere from the fuel supply for an internal combustion engine having an intake manifold for distributing a mixture of fuel and air to individual cylinders of said engine, a carburetor having air and fuel inlets for supplying a mixture of air and fuel to an inlet on said intake manifold, a fuel bowl associated with the carburetor for supplying fuel to said fuel inlets, an air horn on the carburetor for mounting an air filter at the air inlet to said carburetor, and means including a fuel tank for maintaining a substantially constant fuel level in said fuel bowl: the improvement in said system which comprises a pair of absorbent beds enclosed in separate closed containers, a first conduit connecting at its opposite ends with said fuel tank above the usual fuel level therein and one side of one of said containers, an atmospheric vent at an opposite side of said one of said containers, a second conduit, connecting at its opposite ends with said first conduit, intermediate its ends, and one side of the other of said containers, means connected at an opposite side of said other container for selectively opening or closing a vent from said other container to atmosphere, third and fourth conduits separately connected at their opposite ends with said intake manifold, and the top of said fuel bowl, respectively, and at spaced apart locations on said second conduit between opposite ends thereof, valve means in said second conduit for alternatively or simultaneously opening and closing communication of suction in said intake manifold by way of said third conduit with said one container and said tank or with said other container and said fuel bowl, and a fifth conduit connected at its opposite ends with the air horn of said carburetor and said other container between said selective venting means and said other container.
2. System as defined by claim 1 wherein said absorbent beds comprise activated carbon beds.
References Cited UNITED STATES PATENTS 3,001,519 9/1961 Dietrich et al. 123-136 3,093,124 6/1963 Wentworth 123136 3,191,587 6/1965 Hall 158.-36.4 3,221,724 12/1965 Wentworth 123-136 LAURENCE M. GOODRIDGE, Primary Examiner.