The present disclosure generally relates to a fuel vapor emission system and its accompanying fuel vapor canister for the treatment of fuel vapor associated with an internal combustion engine.
An Evaporative Emission Control System (EVAP) may be coupled to an internal combustion engine to prevent fuel vapors (e.g., gasoline vapors) from escaping from a fuel tank and fuel system into the atmosphere.
A common EVAP system includes a carbon canister (a.k.a. fuel vapor canister or fuel canister) that uses one or more types of activated carbon to capture fuel vapor through adsorption. When an internal combustion engine is not running, fuel vapor from the fuel tank may be passed through activated carbon of the carbon canister so that the fuel vapor is adsorbed therein. That is, air mixed with fuel vapor moves from the fuel tank to the carbon canister via a load port to ensure fuel vapor is not released to the atmosphere. After the fuel vapor/air mixture enters the carbon canister via the load port, activated carbon in the carbon canister adsorbs the fuel vapor in the mixture and clean air (or generally clean air) leaves the carbon canister and is generally allowed to escape to the environment.
There may be, however, practical limits as to how much fuel vapor that can be adsorbed by the activated carbon. As such, when the engine is running, the EVAP system directs “clean” air through the activated carbon to purge the fuel vapor from the carbon (a.k.a. desorption). The purged fuel vapor is then generally passed, via a purge port, to an air intake manifold of the engine where it is used to augment combustion.
To reiterate, when an engine is not running, the EVAP generally directs fuel vapor into a carbon canister via a load port so that the activated carbon in the canister may adsorb the fuel vapor. When the engine is running, one or more purge cycles occur, causing the fuel vapor to be desorbed from the fuel canister and conveyed via a purge port into an engine air intake manifold to augment combustion. The desorption that occurs during the purge cycle ensures that the fuel vapor filtering medium (e.g., activated carbon) does not become saturated such that it no longer captures fuel vapor when needed.
A common carbon canister may include one or more chambers (a.k.a. bed volumes) fluidly coupled together, where each chamber is generally filled with some type of activated carbon. Often, each chamber is longer than it is wide. Further, one or more chambers may include a spring employed to apply pressure to the activated carbon in the respective chamber. These springs are generally positioned such that the force applied by the springs is in the direction along the length of each of the respective chamber. Among other things, the springs may ensure a generally tight pack of the activated carbon.
A load port and a purge port are often located protruding from one end of the chamber(s) that is opposite the spring end. This configuration often helps to ensure that any condensed fuel vapor (i.e., liquid fuel) drawn in during a purge cycle is not conveyed to an air intake manifold of an engine. However, due to the size of such configurations, it can be challenging to find space to accommodate these types of carbon canisters. That is, devices that use these common carbon canisters, such as vehicles or generators, often have size constraints that make finding space to accommodate a carbon canister difficult.
Accordingly, there is a need for carbon canisters that accommodate the space requirements often encountered when designing devices that employ an internal combustion engine.
Referring to the discussion that follows and the Figures, illustrative approaches to the disclosed systems and methods are described in detail. Although the Figures represent some possible approaches, the Figures are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the descriptions set forth herein are not intended to be exhaustive, otherwise limit, or restrict the claims to the precise forms and configurations shown in the Figures and disclosed in the following detailed description.
With reference now to
The canister includes, in part, a load port 106 where fuel vapor from the tank 104 enters the canister 102, a housing 108 having three bed volumes 110, 112, 114, a cap 116 covering openings of the three bed volumes 110-114, a coupling 118 (a.k.a. pass-through connector) that fluidly couples the first bed volume 110 to the second bed volume 112, and a purge port 120 where fuel vapor is expelled during a purge cycle. The coupling 118 may include a mounting portion 121 to at least partially secure, and in some approaches fully secure, the fuel canister 102 within a vehicle (not shown) or engine compartment.
The EVAP 100 may also include a canister vent solenoid valve (CVS) and filter 122 coupled to the canister 102. In other examples, however, the CVS 122 could instead be a leak detection valve, an evaporative system integrity module (ESIM), a fuel tank isolation valve (FTIV), or an electronic leak check module (ELCM).
Though not shown in
In one example, the first and second bed volumes 110, 112 may include pelletized carbon adsorbents with a butane working capacity (BWC) typically greater than 8 g/dL. Further, the third bed volume 114 may include extruded particle carbon (a.k.a. MPAC 1), as described in U.S. Pat. No. 9,174,195, which is incorporated herein by reference in its entirety. The particle arrangement of MPAC 1 is advantageous for space-constrained applications since the particle allows for the third bed volume 114 to be of various shapes and does not require the continuous length that is often needed for a honeycomb monolith typically longer than 100 mm.
While the exemplary EVAP 100 of
As pressure increases in the fuel tank 104, a mixture 124 of air and fuel vapor from the tank 104 may enter through the load port 106 so that it may be conveyed through the fuel vapor filtering medium in the first, second, and third bed volumes 110-114. As such, the fuel vapor in the mixture 124 is adsorbed by the fuel vapor filtering medium(s) in each bed volume 110-114 and clean air is expelled via the CVS 122. This cycle, that includes the flow of the mixture 124 into the load port 106 and through the fuel vapor filtering medium(s), may be referred to as a flow or load cycle.
When an engine (not shown) is operating, a purge cycle may be employed to “clean” the fuel vapor filtering media. During an exemplary purge cycle, air from the environment is drawn through, for example, the CVS 122 and passed through the third bed volume 114, the second bed volume 112, the coupler 118, and then through the first bed volume 110 before exiting the purge port 120. The air passed through the canister 102 during the purge cycle causes fuel vapor that was previously adsorbed by the fuel vapor filtering medium during the load cycle to be resorbed into air passing therethrough. The resorbed fuel vapor that passes out the purge port 122 may be directed to an engine air intake manifold (not shown) where it can be used to augment combustions.
Having the purge port 122 and the load port 106 protrude from the side of the canister 102 allows for a more compact design of the canister 102, making it easier for those that design engines to find space to accommodate the canister 102.
As will be described below with respect to
With reference now to
Referring now to
The exemplary canister 102 further includes a first spring 145, a first end plate 146 (which is permeable to fuel vapor), a first filtering insert 148, and a second filtering insert 150. When assembled (see, e.g.,
Similarly, the canister 102 also includes a second spring 152 that applies a force through a second end plate 154 (also permeable to fuel vapor), a third filtering insert 156, through a fuel vapor filtering medium (not shown) in the second bed volume 112 to a fourth filtering insert 158, which is positioned towards the fourth opening 140 of the second bed volume 112. This force helps to keep the fuel vapor filtering medium contained in the second bed volume 112 and minimizes voids in the filtering medium.
Further details regarding the configuration of the springs 145, 152, end plates 146, 154, filtering inserts 148, 150, 156, 158, and fuel vapor filtering mediums will be described below with respect to
With continued reference to
The filtering inserts employed may include, for example, foam, fleece, and/or other filtering materials permeable to fuel vapor, but impermeable to other unwanted elements. Further, the filtering elements represented in
Also shown in
With continued reference to
As shown in
Referring now to
With continued reference to
Though not shown, the air/fuel vapor mixture leaving the purge port 120 can be fed into an engine where it may be used to augment combustion.
Due to the dynamics of the flow during the purge cycle 132, fuel vapor that has condensed in the cap 116 or load port 106 may be drawn 172 into the first bed volume 110. However, since the window(s) 171 of the purge control insert 168 are embedded within the fuel filtering medium, the risk of liquid fuel being conveyed out the load port 120 is minimized. Details regarding how the windows 171 of the purge control insert 168 are embedded within the fuel filtering medium are described below with respect to
Referring now to
The exemplary fill line 174 of
In one example, the purge windows 171 sum an area of 64 mm2, the purge port 120 has a cross-sectional area of 34.63 mm2, and the buffer volume 176 is about 100 cc. The location of the purge control receptacle 170 and the accompanying insert 168 may vary along the length of the first bed volume 110, as indicated by an arrow 179 along the housing 108.
Further, the dimensions and shape of the purge receptacle 170 and the corresponding purge control insert 168 may also vary based on needs. For example, the dimensions of the purge control insert 168 and the associated receptacle 170 may be changed to lower the purge control window(s) 171 deeper into the first bed volume or to raise the purge control window(s) 171 higher in the first bed volume.
By changing the position of the purge window(s) 171, the amount (e.g., the buffer volume 176) of filtering medium that condensed fuel vapor passes through may be changed. To illustrate, see
Each insert 200-204 of
As shown in
A canister (see, e.g., the canister 102 of
The implementation of purge control insert opens up manufacturing possibilities. For example, different customers may request differing buffer volumes. In such scenarios, the same canister (e.g., the canister 102 of
While not shown, each window 210 of
Referring now to
The canister 300 of
The canister 302 also includes a coupler or coupling cap 316 that fluidly couples the first bed volume 302 to the second bed volume 308. Sonic welding may for example, be employed to connect the coupler 316 to the first and second bed volumes 302, 308.
Similarly, there is a second spring 326, a second permeable end cap 328, a third-end filtering element 330, and a fourth-end filtering element 332 associated with the second bed volume 308. The second spring 326 applies pressure to the second permeable end cap 328, that in turn applies a pressure to the filtering medium 314 within the second bed volume 308, thus minimizing voids in the filtering medium 314 of the second bed volume 308.
Referring back to the first bed volume 302, a purge control insert 334 is coupled to a side wall 336 of the first bed volume 302. The purge control insert 334 includes an insert filter 338 (e.g., a fleece or foam) that covers a window 340 of the purge control insert 334. The insert filter 340 keeps the filtering medium 340 in the first bed volume 302.
Purge air 342 is represented passing through the second bed volume 308 and the first bed volume 302. The purge air 342 draws out fuel vapor from the filtering medium 314 in each bed volume 308, 302 and passes this fuel vapor out the window 340 of the purge control insert 334 so that it may pass through a purge port 344 where it may eventually be used to augment combustion.
During the flow of the purge air 342, condensed fuel 346 (i.e., fuel vapor that may have condensed in the cap or load port) may be drawn 347 into the first bed volume 302. For example, the condensed fuel vapor 346 may pass the first spring 318, through the first permeable end cap 320 and the first-end filtering element 322 and into the filtering medium 314 of the first bed volume 302. If this happens, a wall 348 of the purge control insert 334 ensures the condensed vapor 346 will pass through a buffer volume of the filtering medium 314 that is determined by a height 350 of the wall 348. If the height 350 of the wall 348 is increased, the buffer volume will increase. In contrast, if the height 350 of the wall 348 decreases, then the buffer volume decreases.
Passing the condensed vapor through the first-end filtering element 322 and a buffer volume of the filtering medium 314 minimizes the chances liquid fuel will leave the purge port 344. If some condensed vapor makes it through the window 340, a reservoir 352 may contain it so it does not pass through the purge port 344.
With reference now to
Forming the first bed volume includes forming a purge control receptacle on a side of the first bed volume. The purge control receptacle may be closer to the first opening than to the second opening of the first bed volume. The purge control receptacle is configured to receive a first purge control insert. The purge control insert is configured to ensure that unfiltered fuel vapor condensate drawn in during a purge cycle is drawn through a first portion (a.k.a. buffer volume) of the fuel vapor filtering medium. Further, the purge control insert is also configured to allow purge air to pass therethrough before leaving a purge port.
Technique 400 also includes forming a second bed volume having a third opening and a fourth opening opposite the third opening at block 404. The second bed volume is also configured to house the fuel vapor filtering medium. The fuel vapor filtering medium in the second bed volume need not be the same as the fuel vapor filtering medium in the first bed volume.
Forming the first and second bed volumes may be carried out via injection molding or some other molding process. For example, a housing may be molded to create the first and second bed volumes. Further, the first bed volume need not be formed before the second bed volume. Rather, the first bed volume may be formed after the second bed volume or at the same time the second bed volume is formed.
Technique 400 may also include creating the first purge control insert that fits within the purge control insert receptacle at block 406. The first purge control insert may be formed such that the purge control insert has at least one opening to allow purge air to pass therethrough before exiting the purge port. Creation or formation of the purge control insert may also include creating a wall on the purge control insert that contains the first portion of the fuel vapor filtering medium in the first bed volume and does not allow passage of the purge air, thus creating a buffer volume of filtering medium that fuel condensate may flow through.
Technique 400 may further include forming or molding a bed volume coupler that fluidly couples the second opening of the first bed volume to the fourth opening of the second bed volume at block 408. The bed volume coupler may be formed to allow the load and purge ports to be positioned on the same side of the canister housing as the bed springs, thus allowing for a compact design. Further, the bed volume coupler may be formed to include a mounting portion that may be employed to mount the fuel canister to an engine compartment.
Similar to above, the bed volume coupler need not be formed after the first or second bed volumes, but rather before or during formation of the first and/or second bed volumes.
With continued reference to
Upon placing the purge control insert into the receptacle, the technique 400 may come to an end. Alternatively, additional steps may be carried out to complete a build of the EVAP canister.
Referring now to
Upon identifying the dimensions of the receptable, process control proceeds to block 504, where determining a buffer volume for an application is carried out. Different clients may require different buffer volumes for their particular application. As such, the buffer volume may include receiving buffer volume characteristics from a client. It is noted that block 504 may instead be carried before block 502, or during block 502.
Once the purge control receptacle dimensions are identified and the buffer volume is determined, process control proceeds to block 506, where forming a purge control insert comporting with the determined buffer volume and the identified purge control receptacle dimensions is carried out. In other words, the purge control insert is formed to fit into the purge control insert receptacle. Further, the purge control insert is formed to meet the buffer volume requirements. This may include forming one or more windows in the insert and forming an insert wall above the windows to ensure that any fuel vapor condensate that makes its way into a filtering medium of a first bed volume during a purge cycle passes through the identified buffer volume of the filtering medium.
After forming the purge control insert, the technique 500 may come to an end.
With regard to the processes, techniques, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain examples, and should in no way be construed so as to limit the claims.
Further, when introducing elements of various embodiments of the disclosed materials, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Next, any numerical examples in the following discussion are intended to be non-limiting, and thus additional numerical values, ranges, and percentages are within the scope of the disclosed embodiments. Still further, the use of terms such as “first,” “second,” “third,” and the like that immediately precede an element(s) do not necessarily indicate sequence unless set forth otherwise, either explicitly or inferred through context.
While the preceding discussion is generally provided in the context of a material used in connection with vehicles, it should be appreciated that the present techniques are not limited to such limited contexts. The provision of examples and explanations in such a context is to facilitate explanation by providing instances of implementations and applications. The disclosed approaches may also be utilized in other contexts or configurations, such as the context of other systems that employ an internal combustion engine that may not be a vehicle.
While the disclosed materials have been described in detail in connection with only a limited number of embodiments, it should be readily understood that the embodiments are not limited to such disclosed embodiments. Rather, that disclosed can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosed materials. Additionally, while various embodiments have been described, it is to be understood that disclosed aspects may include only some of the described embodiments. Accordingly, that disclosed is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This application claims priority to U.S. Provisional Application No. 63/440,367, filed on Jan. 20, 2023, the contents of which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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63440367 | Jan 2023 | US |