Patent ID: 12209561

The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIG.1schematically illustrates a portion of an example evaporative fuel system10. The system10includes a fuel tank12having a fuel filler14with a fill cap16. A fuel pump18supplies gasoline, for example, from the fuel tank12to an internal combustion engine20.

The system10is configured to capture and regulate the flow of fuel vapors within the system. In one example, a fuel tank isolation valve24is arranged fluidly between the fuel tank12and a charcoal canister22, which captures and stores fuel vapors for later use by the engine20. A purge valve26is fluidly connected between the charcoal canister22and the engine20. A controller11regulates a position of the purge valve26to selectively provide the fuel vapors to the engine20during operation to make use of these fuel vapors.

The integrity of the system10must be periodically tested. One type of system10uses a leak detection module (LDM)28, which can be used to pull a vacuum and/or pressurize the system to determine whether a leak exists, for example, using a pressure transducer30. In one example leak test procedure, the purge valve26is closed and the controller11operates the leak detection module28to pressurize the system. Any change in pressure detected by the pressure transducer30, which is monitored by the controller11, is indicative of a leak.

One example leak detection module28is shown in more detail inFIG.2A. The module28includes a pump32, which receives atmospheric air through an inlet port34. The pump provides pressurized air to an outlet port36, which may be supplied through a check valve38to the charcoal canister22or other evaporative component of the system10.

The pump32has a housing40that is constructed from first and second plates42,44secured on either side of an intermediate plate46. In the example, the inlet and outlet ports34,36are provided on an edge of the intermediate plate46rather than being provided on one or both of the first and second plates42,44. Referring toFIGS.2A and2B, the intermediate plate46has a first side46aadjacent to and in abutment with the first plate42, and a second side46bis adjacent to and in abutment with the second plate44. In the example, the first and second sides46a,46babut and engage the first and second plates42,44without any additional sealing structure (e.g., gaskets or sealant) therebetween. A motor48is mounted to the first plate and rotationally drives a rotor52received in a bore62of the intermediate plate46via a shaft50.

In the example, the first, second, and intermediate plates42,44,46are constructed from a plastic material, such as nylon or polypropylene, for example, which may be graphite- or Teflon-filled. In one example, the plastic is injection molded, which provides surfaces having characteristics that are identifiable and indicative of the molding process (such as shrinkage and flow lines). The plates42,44,46include at least two locator holes54that are each configured to temporarily receive a through-pin during assembly of the pump32to precisely align the plates with one another. Fasteners56are received in fastener holes58in the first, second, and intermediate plates42,44,46. In the example, the ends60of the fasteners56, which may be metal, are plastically deformed to securely retain the first and second plates42,44in a clamping relationship about the intermediate plate46. Threaded fasteners, rivets or other types of fastening may also be used.

The example pump32is a rotary vane configuration. Referring toFIGS.3A and3B, an elliptical bore62is illustrated. The rotor52includes multiple slots64about its circumference. The slots64slidably receive vanes66that are moveable within the slot to seal against the periphery of the bore62from centrifugal forces, as is known in rotary vane pumps. For the elliptical bore62, two cavities80,82are provided to create a two-chamber configuration that balances pressure across the rotor52.

Referring toFIG.4A, the intermediate plate46is reversible such that either side46a,46bmay mate with either the first and second plate42,44. That is, the intermediate plate46is symmetrical about an axis A such that first and second surfaces72a,72brespectively provided by the first and second sides46a,46band their corresponding fluid passages are the same if rotated 180° about the axis A. In one example, these surfaces72a,72bare unmachined (i.e., left as-molded, without lapping) as the disclosed pump configuration is sufficiently leak-tight such that more precise surfaces are not needed. But, machining may be used, if desired, to make the pump more leak-tight.

A first passage74aon the first side46afluidly connects the inlet34to the bore62, as shown inFIGS.3A and4A. The first passage74aincludes a first passageway76afluidly connected to the ambient side V of first cavity80and a second passageway78afluidly connected to the ambient side V the second cavity82. The pocket68ais arranged in the first passage74afluidly between the inlet port34and the bore62.

In a similar manner, a second passage74bon the second side46bfluidly connects the outlet36to the bore62, as shown inFIG.4B. The second passage74bincludes a first passageway76bfluidly connected pressure side P of the second cavity82and a second passageway78bfluidly connected to the pressure side P of the first cavity80. The pocket68bis arranged in the second passage74bfluidly between the outlet port36and the bore62.

At least one of the pockets68a,68breceives a filter70(e.g., foam), but both pockets68a,68bmay include a filter70if desired. In this manner, contaminants are filtered from the system10and no external lines or fittings are needed as the internal filter is contained within the pump32. The LDM28does not require protection against ISO ultrafine dust (1-22 micron) due to its lack of a calibration orifice, which is incorporated in some types of leak detection pumps. The type of foam filter elements which may be incorporated into the LDM28may not prevent ultrafine dust from entering the pump assembly. But, this is not a risk to pump performance due to the relatively low concentration of dust relative to the volume of air passing through the pump32.

Another rotary vane configuration is shown inFIG.5, which illustrates an intermediate plate146with a circular bore162having a single crescent-shaped cavity. In this example, the first side146aand its first surface172ahave a first passage174afluidly connecting the pocket68ato ambient side V of the bore162. The intermediate plate146is reversible. As shown inFIG.6, the second side146band its second surface172bhave a second passage174bfluidly connecting the pocket68bto pressure side P of the bore162.

During manufacturing of the pump, the first plate42is arranged into abutting engagement with either the first side46aor the second side46bof the intermediate plate46. That is, the intermediate plate is reversible with respect to the first and second plates42,44. The rotor52is disposed along with slidable vanes66into the bore62. The second plate44is arranged into abutting engagement with the other of the first and second sides46a,46b. The first and second plates42,44are secured about the intermediate plate46and rotor52. The motor48is mounted to the first plate42, coupling the motor48to the rotor52.

It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention.

Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. For example, the disclosed pump may be used in applications other than vehicle evaporative systems.

Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.