Air filtration apparatus

An air filter assembly for an evaporative emissions control canister used with an internal combustion engine fuel system. The assembly includes: a housing having: an air inlet formed in an upper portion of the housing; and an air outlet; and; a baffle disposed within the housing. The baffle extends vertically downward from the air inlet in the upper portion of the housing towards a bottom portion of the housing. The baffles forming a plurality of vertically extending channels interconnected through a horizontally interconnecting channel formed between a bottom edge of the baffle and the bottom portion of the housing. A first one of the vertically extending channel receives air entering the housing from the air inlet. The air passes downwardly in the first one of the channels, then passing laterally outwards through the horizontally interconnecting channel towards sidewalls of the housing, then passing upwardly through a second one of the vertically extending channels, and then finally exiting the housing through the air outlet. A filter structure is disposed in the second one of the vertically extending channels.

TECHNICAL FIELD

This disclosure relates generally to air filtration apparatus and more particularly to air filtration apparatus for use with fuel vapor recovery system. Still more particularly, the disclosure relates to an air filter for an automotive vehicle fuel vapor recovery system, which includes structures for gradually separating unwanted particles of dust, moisture, soot, and the like from the vapor recovery system purge air stream.

BACKGROUND

As is known in the art, Conventional fuel vapor recovery systems used in automotive vehicles typically include a carbon canister used to recover excess fuel vapor generated in the fuel tank. Activated carbon in the carbon canister adsorbs the fuel vapor and temporarily retains the vapor until the canister is purged. During vehicle operation, at times determined by programmed vehicle calibration, the fuel vapor adsorbed by the activated carbon is desorbed by introducing outside air, or purge air, to the canister. The fuel vapor thus desorbed is fed to the engine for utilization in combustion.

More particularly, automotive internal combustion engines utilize a carbon canister connected to the fuel tank to collect fuel vapors from the fuel tank as the tank is being refilled, or when the vehicle is parked. The canister connected to the engine also allows the vapor stored within the canister to be pulled to the engine for burning during the “purge” cleansing process. Filtered fresh air is necessary for the purging process so that environmental contaminates do not eventually plug the carbon bed or damage some valves which may lead to the generation of On Board Diagnostic (OBD-II) detection faults. An air filtering apparatus with a built-in Canister Vent Valve (CVV) can become an important design element assuring the supply of this clean air.

Filtering of-purge air introduced to a vapor recovery system to purge the carbon canister is not new. For the mentioned purpose, prior art examples teach the use of one or more assemblies comprising either a filter medium, baffle means, or both. More particularly, U.S. Pat. No. 5,058,693 to Murdock et al, U.S. Pat. No. 5,024,687 to Waller, and U.S. Pat. No. 5,638,786 to Gimby each disclose a remote fuel vapor recovery system filter assembly comprising the combination of baffle and filter element means. Both '693 and '687 include simple baffle means comprising no more than two independent baffle entities. The present disclosure discloses a plurality of mating and nonmating planar baffles, the increased complexity of which is matched by increased functional efficiency. Patent '768 provides a self-cleaning air filter comprising a filter element of various embodiments. In each embodiment, this mentioned element, so that it may be cleaned by the disclosure's filter cleaning member, is apparently a thin, firm, screen-like entity, and the filter includes provisions for function upon “occlusion” of this element. The present disclosure is comprised of a robust and hearty (thick, wide and tall) filter element and a baffle area, and has been proven to be able to last the average lifetime usage of vehicles (approximately 150,000 miles) without any cleaning.

There are two primary and novel factors contributing to the long-lasting functionality of our disclosure. The first is found in the design of the baffle section. The plurality of baffles are designed such that the particles, having wide size and inertial distributions, are dislodged from the air stream as it travels from inlet towards the filter section. This occurs due to decreased baffle spacing between baffles and the corresponding increase in mobility demand placed on the air flow. The second primary and novel quality of our disclosure is found in the implementation of a filter element so that the smallest particles (those that survive the baffle section) are generally lodged in the upper half of the filter element and eventually, due to gravity, vibration, etc., will migrate to the lower portions of the element. This occurrence will ensure the thorough cleaning of the air and the long-lasting function of the air filter assembly.

U.S. Pat. No. 4,693,393 to DeMinco et al and U.S. Pat. No. 5,501,198 to Korama disclose examples of filtering systems integrally combined within a carbon canister by comprising only baffle means and only filter element means, respectively. U.S. Pat. No. 5,149,347 to Turner et al also discloses a separator device comprising only a baffle section, which is remotely connected to the carbon canister. It is apparent that any structure comprising only baffle means or only filter means will not be as effective and robust as the present disclosure comprising both baffle and particulate filter means.

U.S. Pat. No. 5,912,368 to Satarino et al., describes a filter that both graduated baffle separation means and filter element means are included in a filter assembly. This assures a maximum degree of separation of particles, foreign matter, such as soot and road dust, moisture, and the like from the fresh air therein otherwise present.

SUMMARY

In accordance with the present disclosure, an air filter assembly is provided for an evaporative emissions control canister used with an internal combustion engine fuel system. The assembly includes: a housing having: an air inlet formed in an upper portion of the housing; and an air outlet; and; a baffle disposed within the housing. The baffle extends vertically downward from the air inlet in the upper portion of the housing towards a bottom portion of the housing. The baffles forming a plurality of vertically extending channels interconnected through a horizontally interconnecting channel formed between a bottom edge of the baffle and the bottom portion of the housing. A first one of the vertically extending channel receives air entering the housing from the air inlet. The air passes downwardly in the first one of the channels, then passing laterally outwards through the horizontally interconnecting channel towards a sidewalls of the housing, then passing upwardly through a second one of the vertically extending channels, and then finally exiting the housing through the air outlet. A filter structure is disposed in the second one of the vertically extending channels.

In one embodiment, the filter structure is disposed adjacent the upper portion of the housing.

In one embodiment, the air outlet is disposed between the upper portion of the housing and a first portion of a sidewall of the housing.

In one embodiment, the second one of the vertically extending channels has a first portion disposed between a first surface portion of the baffle and a first sidewall portion of the outlet. The first sidewall portion of the outlet is disposed within the housing. The second one of the vertically extending channels has a second portion disposed between a second surface portion of the baffle and a second sidewall portion of the housing.

In one embodiment, a first portion of the filter structure includes: a first filter member having: a first portion disposed between the first surface portion of the baffle and the first sidewall portion of the outlet; and a second portion disposed between the second portion of the baffle and a space between a lateral edge of the first filter element and the second sidewall portion of the housing.

In one embodiment, the filter structure includes a second filter member disposed above the first filter member. The second filter member has: a first portion disposed between the first surface portion of the baffle and a second surface portion of the outlet; and a second portion extending between the second surface portion of the baffle and the second sidewall portion of the housing and over the space between the lateral edge of the first filter element and the second sidewall portion of the housing.

DETAILED DESCRIPTION

FIG. 1shows an automotive evaporative emission system having a fuel vapor storage system (FVSS) integrally disposed therein. Although some of the automotive evaporative emission system's specific, geometry, and component names may differ from vehicle to vehicle, the primary structure and structural components will remain constant.

Primary components of automotive evaporative emission system are fuel tank10and internal combustion engine12. Liquid fuel enters the vehicle by first being introduced to the fuel inlet opening14then traveling through fuel filler tube16into fuel tank10. Fuel is sent by fuel pump18through fuel filter20and to engine12by way of fuel line22, fuel rail24, and fuel injectors26. Optionally, some systems will recycle fuel unused by engine12by sending it back to fuel tank10via the fuel return line28.

There are generally two primary circumstances wherein fuel vapor filled air is forced out of fuel tank10. The first circumstance is during the above outlined filling of tank10and the other occurs when the fuel vapor in the tank expands (usually due to increased temperature of the fuel and/or fuel vapor) and forces some of the fuel vapor out of the tank. In either case, the fuel vapor filled air is sent through fuel recovery line30to carbon canister32where it is cleaned of its vapor before being sent to the atmosphere. Carbon canister32is filled with activated carbon which adsorbs the fuel vapor from the air flow.

Periodically, carbon canister32, after absorbing and cleaning the fuel vapor filled air, must be desorbed, or purged, of the fuel vapor therein. This refreshing is done so that the canister can accommodate and absorb additional fuel vapor from fuel tank10.

Atmospheric air, to be used as purge air, is forced into and out of canister32and then sent through vapor purge line34, and canister purge valve36, directly to engine12for utilization.

As mentioned above, the outdoor air used as purge air must be cleaned of substantially all matter before it is introduced to canister vent valve38(CVV) and carbon canister32. This is the purpose of the air filter assembly40contained along with the CVV38in a housing70.

The preferred design of the air filter assembly40is best viewed inFIGS. 2-5. Briefly, the air filter assembly40has integrated mounting features that enable the assembly to be installed directly to the carbon canister32. Further, the air filter assembly40includes therein the canister vent valve (CVV)38in addition to a circularly baffles50(FIG. 4) and a filter structure58(FIGS. 4,4A). An inlet air port60is provided for incoming fresh air and an outlet port62(FIG. 4) is provided and coupled to the CVV38, as indicated nFIG. 1. It is noted that the CVV38may be a built-in or plug in part of the housing70. The valve38may be an electrical, mechanical, pneumatic or other device to allow the opening/closing of the flow path by microcontroller, not shown.

More particularly, the baffle50is a hollow tube-like structure, here for example, a circular tube-like structure, extends vertically downward from the air inlet60in the upper portion71of the housing70towards, but short of by about 5 to 10 mm, a bottom portion73of the housing70, to thereby form a gap or horizontal channel52adjacent to bottom portion73of the housing70. The baffle50forms a plurality of, here two, vertically extending channels80,82interconnected through the horizontally interconnecting channel52formed between a bottom edge of the baffle50and the bottom portion73of the housing70. A first one of the vertically extending channels, here channel50, receives air entering the housing70from the air inlet60. The air passes downwardly in the first one of the channels80(FIG. 5), then passing laterally outwards through the horizontally interconnecting channel52towards sidewalls90of the housing70, then passing upwardly through a second one of the vertically extending channels, here channel82and then finally exiting the housing70through the air outlet62.

It is noted that the filter structure58is disposed in the second one of the vertically extending channels. Further, it is noted that the filter structure58is disposed adjacent the upper portion71of the housing70. Still further, it is noted that the air outlet62is disposed between the upper portion71of the housing and a first portion93of a sidewall of the housing70and a second wall portion97. The second one of the vertically extending channels82has a first portion disposed between a first surface portion95of the baffle50and a first sidewall portion91of the outlet62. The first sidewall portion91of the outlet62is disposed within the housing70. The second one of the vertically extending channels82has a second portion disposed between a second surface portion99of the baffle and a second sidewall portion100of the housing70.

A first portion58aof the filter structure58(FIG. 4,4A) includes: a first filter member having: a first portion58a1disposed between the first surface portion95of the baffle50and the first sidewall portion91of the outlet62; and a second portion58a2disposed between the second portion99of the baffle50and a space102between a lateral edge of the first filter element58aand the second sidewall portion100of the housing70. The filter structure58includes a second filter member58bdisposed above the first filter member58a. The first filter member58bhas a greater porosity than the porosity of filter member58a. The second filter element58bhas: a first portion58b1disposed between the first surface portion95of the baffle50and a second surface portion91of the outlet62; and a second portion58b2extending between the second surface portion99of the baffle50and the second sidewall portion100of the housing70and over the space102between the lateral edge of the first filter element58aand the second sidewall portion100of the housing70.

The new filtration design provides effective filtration in various orientations and limits flow restrictions during dust ingestion. The filtration strategy has three steps. First, the circular baffle50guides the outside air from the vent inlet port60to impinge against the bottom surface of the filter structure58as shown inFIG. 5, and change the air flow direction abruptly as the air passes though the horizontal channel52to reduce the velocity of the air. This helps block some dust in the air. Second, two layers of filter structure58, i.e., filter member58aand filter member58b, with different density (i.e., porosity) slows down the air flow rate and filters more dust to allow clean air to passes through the filter structure58. The upper filter member58bis less dense than the lower filter member58a. In the early stage of the filtration apparatus, the air flow pattern is attracted to the open access of the straight baffle50, as shown inFIG. 5. After the dust gradually being caught by the portion of the lower filter member58a, such lower filter member58acloses to the open access and therefore the flow becomes more restrictive. The flow pattern will be shifted to other (i.e., outer) side of the filter58, as shown inFIG. 6, in the late stage of the filtration. Third, the straight baffle50makes the air flow changing direction abruptly to reduce the velocity of the air, as shown inFIGS. 5 and 6.

In addition to the filtration function, the filtration device also reduces the complexity. The baffle50is molded directly in the filter structure58. The mold-in mounting features are for installing the filter device into the canister directly; and built-in CVV for Vehicle is for the vehicle OBDII leak check function. Therefore, it reduces the complexity of parts. The filters58a,58bmay be supported within the housing70by any convenient means such as by thin posts (not shown) projecting into the surface of the filter58afrom the bottom housing while the circular tube constrains the lateral motion of the filters58a,58b.

A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.