US3393669A - Apparatus and process for adsorbing and desorbing internal combustion engine fuel vapors - Google Patents

Description

y 23, 1968 J. VARDI ETAL 3,

APPARATUS AND PROCESS FOR ADSORBING AND DESORBING INTERNAL COMBUSTION ENGINE FUEL VAPORS Filed May 19, 1966 EXHAUST 2| GASES ACTIVATED CARBON BED AIR CLEANER INTAKE MANIFOLD 2 FUEL TANK FUEL PUMP Joseph Vordi D i 11 w Inventors Patent Attorney United States Patent APPARATUS AND PROCESS FOR ADSORBING AND DESORBING INTERNAL COMBUSTION ENGINE FUEL VAPORS' Joseph Vardi, Elizabeth, and David T. Wade, Metuchen,

N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed May 19, 1966, Ser. No. 551,411

9 Claims. (CL. 123-136) ABSTRACT OF THE DISCLOSURE Apparatus and process for opening an internal combustion engine which comprises adsorbing fuel constituents on an adsorbent bed when the engine is not operating; thereafter during engine operation desorbing said constituents from saidbed first utilizing a hot backwash purge and thereafter utilizing a cold backwash purge.

The present invention is broadly concerned with an adsorb vaporized fuel constituents and then desorbs these fuel constituents and combusts the same in the engine. The invention is particularly directed toward a unique desorption technique wherein adsorbed constituents are eificiently desorbed by the use of a hot-cold purge.

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 fuel constituents which are emitted through the vent in the fuel storage tank and through vents from the carburetor bowl. For example, it has been estimated that from about 10 to 20% by volume as, for example, about 15%, by volume of the total vapors and fumes emitted to the atmosphere from an internal combustion motor vehicle are evaporated from the gasoline tank and the carburetor bowl.

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 by a hot-cold purge and combusted in the engine. The adsorbent may be any suitable material which will adsorb fuel constituents such as silica gel, activated carbon, and the like.

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 breathe through the vent, or vents, in the fuel tank thereby emitting fuel constituents into the atmosphere. In many instances the temperature of the fuel reservoir may be from about 20 to 40 F. higher than the atomspheric or ambient temperature.

Furthermore, after the engine has been operated for a period of time and then turned off, the temperature of the fuel in the carburetor bowl rises as heatflows 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 01f. It has been'estimated that the loss from a gasoline tank may range from about 2 to 150 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 by a hot-cold technique and combusted in the internal combustion engine. The process and apparatus of the present invention may be more fully understood by reference to the drawing illustrating an embodiment of the same.

Referring specifically to the drawing, utilizing a single adsorbent bed, vaporized fuel constituents from fuel tank 10 are passed through line 1 and adsorbed in zone 20 containing a suitable adsorbent 21. Liquid fuel is passed to the carburetor bowl 30 by means of line 2, pump 3, and line 4. Vaporized constituents from the carburetor bowl pass into the lower or one end of zone 20 by means of line 31. Air is passed through filter zone 40 and into carburetion zone 50 whereis is mixed with liquid fuel introduced from thecarburetor bowl. A flapper valve 51 controls the amount of air-fuel mixture introduced into intake manifold 60.

When theengine is operating in a conventional operation, a portion of the incoming air is passed through line 22 and enters the other end of zone 20 and backwashes through the adsorbent, thereby desorbing fuel constituents previously adsorbed. The amount of air backwashing is sufiicient to desorb the adsorbed constituents. The backwashing air containing desorbed fuel constituents passes through line 23 and is introduced into the intake manifold 60. The rate of backwashing through line 23 into manifold 60 is controlled by orifice or equivalent means 24, and auxiliary equipment (not shown). In essence, as the engine moves from idling to full throttle the rate of backwashing increases.

In accordance with the specific adaptation of the present invention, when the engine is operating adsorbed constituents are removed from the adsorbent by backwashing air therethrough utilizing initially a hot purge and then a cold purge. This may be secured by a suitable valve timing device 70, or equivalent means which initially permits hot air to be introduced into the other end of zone 20 by. means of line 71. The air for the hot purge may be heated by any suitable means such as heating coils and the like.

However, it is preferred to secure the temperature of the hot purge by introducing atmospheric air into a manifold device wherein the air is heated by the exhaust gases which are introduced into device 80 by means of line 81 and withdrawn by means of line 82. These gases are heated to a temperature above about 200 F., preferably to a temperature in the range from about 400 to 500 F. as, for example, 450 F.

It is to be understood that under certain conditions exhaust gases may be used directly as a backwashing medium. Under these conditions no air is introduced by means of line 72 but at least a portion of hot exhaust gases removed by means of line 82 is introduced into line 71 by means of line 83. Under certain conditions it may be desirable to mix air introduced by means of line 72 and exhaust gases introduced by means of line 83. The temperature of these gases may range from about 700 F. to about 800 F. It is also to be understood that in the manner of operating as described, a temperature gradient will exist throughout the bed. The temperature of the bed at the point the backwashing gases are introduced will approximate the temperature of the incoming gases, while the temperature of the one end of the bed will approximate ambient temperatures. It is also to be understood that it .4 adsorbent bed under conditions to desorb fuel constituents, and to produce a first fuel-enriched mixture, introducing said first fuel-enriched mixture into the manifold of said engine, thereafter under engine operating suction backwashing cold gas into the other end of said adsorbent bed is within the concept of the present invention during the 5 and passing the same through said adsorbent bed under backwashing cycle to introduce cold air continuously conditions to cool said bed and to produce a second fuelthrough line 22 and in the initial cycle or during the hot enriched mixture, introducing said second fuel-enriched purge to heat up the gases introduced by means of line mixture into said manifold of said engine.

22 to the desired temperature by mixing therewith heated 1O 2. Process as defined by claim 1 'Wherein said hot gas air introduced by means of line 72 or exhaust gases incomprises heated atmospheric air.

troduced into the system by means of line 83. Generally, 3. Process as defined by claim 1 wherein said hot gas if the temperature of the bed at the point where the backcomprises engine exhaust gas.

washing gases are introduced is in the range from about 4. Process as defined by claim 1 wherein said fuel is 400 to about 500 F. as, for example, about 450 F., a gasoline and wherein said adsorbent is activated carbon. a satisfactory operation will be achieved. As pointed out 5. Process as defined by claim 1 wherein the temperaheretofore, the gradient temperatures throughout the bed ture of said hot gas is in the range from above ambient will decrease in a manner that ambient temperature will to 800 F. and wherein the temperature of said cold .gas exist at the one end of the bed. is about ambient.

Generally, the time of hot purge is in the range from 6. Process as defined by claim 1 wherein the amount about 2 to 12 minutes as, for example, 3 to 5 minutes. The and temperature of hot gas introduced into said adsonbent desorption is then continued using a cold purge wherein bed is sufficient to raise the other end of said bed to a line 71 is shut off and line 22 opened so as to introduce temperature within the range of about 400 to about atmospheric air into the other end of zone 20. As described 500 F. heretofore, this technique may be modified as desired, by 25 7. Apparatus for preventing loss of fuel constituents into the use of exhaust gases, or by the continuous use of cold the atmosphere from an internal combustion motor which air, and other modifications, etc. In order to further ilcomprises in combination: (1) a fuel reservoir; (2) an adlustrate the invention a number of operations were consorption zone having a one end and another end and conducted utilizing a cold purge only and also utilizing a hot taining an adsorbent therein, (3) an engine manifold compurge followed by a cold purge. The adsorbent was charmunicating with the cylinders of said motor; (4) a first coal. The results are shown in the following table. conduit characterized by being in open communication Time Hydroon Cold Temp. of carbon Final Time on Hot Purge, Min. Purge, Purge, Removal, Percent Temp. Min. F. gm./100 gm. in ed,

Charcoal F.

4.25 4.25 471 19.0 96 104405 3 5.5 433 17.6 89 76-128 Cold Purge Only 8. 5 -80 8. 5 43 -80 Thus in the conventional operation the full adsorption with said one end of said adsorption zone and the upper capacity of the adsorbent is not utilized due to unremoved area of said fuel reservoir; (5) a second conduit characequilibrium level of hydrocarbon from the charcoal. terized by being in communication with said intake mani- However, when following the technique of the present infold and said one end of said adsorption zone; (6) a third vention utilizing a hot purge, above ambient, in the range 45 conduit characterized by being in communication with from about 150 to 800 F. effective removal of the hysaid other end of said adsorption zone and with the atdrocarbons is secured in about 3 to 5 minutes. The purge mosphere; (7) a fourth conduit characterized by being is then changed to cold (ambient) conditions to bring in communication with said other end of said adsorption the temperature of the charcoal back to normal so that zone and a source of hot gases; (8) and a timing device effective adsorption can take place as soon as a hot soak programed in a manner that during engine operation hot period starts. The adsorbent bed size can be reduced by a gases will be, during an initial period, introduced into the factor of 2-3 using this hot purge process. The above table other end of said adsorption zone and subsequent to said demonstrates the effectiveness of the process. initial period atmospheric air will be introduced into the In its broadest adaptation, the present invention covers other end of said adsorption zone, all gases during said the method of operating an engine wherein vaporous conengine operation passing through said adsorption zone, stituents of a fuel are adsorbed on an adsorbent and therewithdrawn from said one end and introduced into said after desorbed by a particular technique from said adsorbmanifold. ent and introduced into an internal combustion engine. The 8. Apparatus as defined by claim 7 wherein said respreferred adaptations are to adsorb vaporous constituents ervoir is the carburetor bowl associated with said engine. from liquid fuel reservoirs which are ahead of the car- 9. Apparatus as defined by claim 7 wherein the said buretor. These vaporous constituents are then desorbed reservoir is a fuel tank associated with said engine. by backflowing or backwashing hot and then cold gases therethrough by the action of the engine and are in- References Clted troduced as an enriched fuel-air mixture into the engine. UNITED STATES PATENTS What clalmed 3,001,519 9/1961 Dietrich et al. 123-136 1. Process of operating an internal combustion en- 3 093 124 6/1963 Wentworth gine which comprises introducing fuel constituents vapor- 3:191:587 6/1965 n 123 136 ized from a liquid pool into one end of an adsorbent bed 3 2 7 4 12/1965 Wentworth 123 136 when said engine is not running, thereafter under engine 3 23 214 2 19 J h 23 X operating suction backwashing hot gas into the other end of said adsorbent bed and passing the same through said AL LAWRENCE SMITH, Primary Examiner.

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