Patent Description:
Evaporative emissions systems have long been required for gasoline powered vehicles. The system must undergo a leak test during a vehicle start-up procedure to ensure that fuel vapors will not leak into the atmosphere. A pump is used either to create a vacuum or pressurize the system. An external filter is used to prevent contamination that could damage the pump or other components of the system during operation. Various valves may be closed during this test procedure to maintain system pressure, and the pressure is monitored to determine if there are any leaks.

The pump used in such a system may be relatively expensive to produce as many of the pump's dimensions are critical, requiring machining. Furthermore, if a multi-plate configuration is used, the plates are unique with respect to one another.

<CIT> teaches a rotor which is eccentric with respect to the axis of the rotor chamber. A housing section is shiftable relative to the end plates to regulate the minimum spacing between the rotor and the housing wall and the degree of fluid seal at that location. The shaft bearings are radial type bearings arranged to transmit axial thrust to the housing to relieve the rotor and vanes of end loading; and the bearings, together with the fluid seals carried on a removable collar, can be removed from the housing for servicing.

<CIT> teaches a dry rotary vane pump having an aluminum bore and rotor with a hard aluminum oxide coating to inhibit wear caused by sliding friction between parts. A Teflon or like plastic coating may be applied to external surfaces of the rotor to further reduce wear and eliminate the need for wear plates at the ends of the rotor.

<CIT> teaches a rotary fluid pump of the type having a housing body and a pair of recessed end heads assembled to opposite ends of the housing. A pair of resilient sealing plates may be disposed between the side of the housing and the recessed end heads to define a rotor chamber having a rotor with slidable vanes mounted thereon. Fluid inlet and outlet ports adapted to communicate with the rotor chamber are formed either in the sealing plates or in the end heads to provide pairs of inlet and outlet ports.

<CIT> teaches a rotary vane pump which has an open ended pump cylinder mounting a drive motor at one end and a ported end plate and sound chamber at the other end. The cylinder contains a rotor mounted to an eccentric drive shaft and having vane grooves receiving slidable vanes contacting an inner diameter of the cylinder. The end plate has an outlet port and primary and secondary inlet ports in communication with the cylinder interior, the inlet ports being in communication with an area of net expansion. The sound chamber has an intake port and an exhaust port in communication with the respective outlet and primary and secondary inlet ports of the end plate. The sound chamber is partitioned to define a number of internal cavities through which the incoming air is routed to the secondary inlet port.

<CIT> teaches methods and systems for diagnosing a vehicle fuel system for a presence or absence of undesired evaporative emissions. In one example, a method comprises conducting a test for undesired evaporative emissions stemming from a fuel system of a vehicle via in a first operating mode, evacuating the fuel system to a variable vacuum level through an entirety of a fuel vapor canister configured to capture and store fuel vapors, and in a second operating mode, evacuating the fuel system to the variable vacuum level through a portion of the fuel vapor canister.

In one exemplary embodiment is a rotary vane pump according to appended claim <NUM>.

In a further example, at least one of the first and second sides includes a pocket with a filter. The pocket is fluidly arranged in one of the first and second passages.

In a further example of any of the above, the first and second plates and the intermediate plate include holes with fasteners that are disposed therein to clamp the first and second plates to the intermediate plate. A motor is mounted to the first plate.

In a further example of any of the above, the first and second plates and the intermediate plate include locating holes that are configured to receive pins during a rotary pump assembly procedure.

In a further example of any of the above, the bore is elliptically shaped. The rotor separates the bore into first and second cavities that are respectively in fluid communication with the first and second passageways.

In a further example of any of the above, the bore is circular that provides a singular cavity having a crescent shape.

In a further example of any of the above, the first and second plates and the intermediate plate are plastic. The first and second sides respectively abut the first and second plates without any additional sealing structure therebetween.

In a further example of any of the above, the first and second sides respectively include first and second surfaces that are unmachined.

In a further example of any of the above, the first and second surfaces are provided by injection molding.

Another exemplary embodiment is an evaporative emissions system according to appended claim <NUM>.

In a further example of any of the above, the evaporative component includes at least one of a charcoal canister and a fuel tank, and includes at least one valve that is arranged a closed position during the leak detection procedure.

In a further example of any of the above, the at least one valve is a check valve and another valve. The check valve is arranged downstream from the outlet port.

In a further example of any of the above, the system includes is a pressure gauge in communication with the controller and is configured to monitor a system pressure during the leak test procedure.

In a further example of any of the above, at least one of the first and second sides includes a pocket with a filter. The pocket is fluidly arranged in one of the first and second passages.

In a further example of any of the above, the first and second plates and the intermediate plate are plastic. The first and second sides respectively abut the first and second plates without any additional sealing structure therebetween. The first and second sides respectively include first and second surfaces that are unmachined.

In an example out with the scope of the claims, but included for reference purposes, is a method of assembling a rotary vane pump includes arranging a first plate into abutting engagement with either a first side or a second side of an intermediate plate that is reversible with respect to the first plate. The method also includes disposing a rotor with slidable vanes into a bore in the intermediate plate. The method further includes arranging a second plate into abutting engagement with the other of the first and second sides. The method further includes securing the first and second plates about the intermediate plate and rotor.

In a further example of the above, the method includes a step of mounting a motor to the first plate. The motor is coupled to the rotor.

In a further example of any of the above, at least one of the first and second sides includes a pocket with a filter.

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.

<FIG> schematically illustrates a portion of an example evaporative fuel system <NUM>. The system <NUM> includes a fuel tank <NUM> having a fuel filler <NUM> with a fill cap <NUM>. A fuel pump <NUM> supplies gasoline, for example, from the fuel tank <NUM> to an internal combustion engine <NUM>.

The system <NUM> is configured to capture and regulate the flow of fuel vapors within the system. In one example, a fuel tank isolation valve <NUM> is arranged fluidly between the fuel tank <NUM> and a charcoal canister <NUM>, which captures and stores fuel vapors for later use by the engine <NUM>. A purge valve <NUM> is fluidly connected between the charcoal canister <NUM> and the engine <NUM>. A controller <NUM> regulates a position of the purge valve <NUM> to selectively provide the fuel vapors to the engine <NUM> during operation to make use of these fuel vapors.

The integrity of the system <NUM> must be periodically tested. One type of system <NUM> uses a leak detection module (LDM) <NUM>, which can be used to pull a vacuum and/or pressurize the system to determine whether a leak exists, for example, using a pressure transducer <NUM>. In one example leak test procedure, the purge valve <NUM> is closed and the controller <NUM> operates the leak detection module <NUM> to pressurize the system. Any change in pressure detected by the pressure transducer <NUM>, which is monitored by the controller <NUM>, is indicative of a leak.

One example leak detection module <NUM> is shown in more detail in <FIG>. The module <NUM> includes a pump <NUM>, which receives atmospheric air through an inlet port <NUM>. The pump provides pressurized air to an outlet port <NUM>, which may be supplied through a check valve <NUM> to the charcoal canister <NUM> or other evaporative component of the system <NUM>.

The pump <NUM> has a housing <NUM> that is constructed from first and second plates <NUM>, <NUM> secured on either side of an intermediate plate <NUM>. In the example, the inlet and outlet ports <NUM>, <NUM> are provided on an edge of the intermediate plate <NUM> rather than being provided on one or both of the first and second plates <NUM>, <NUM>. Referring to <FIG>, the intermediate plate <NUM> has a first side 46a adjacent to and in abutment with the first plate <NUM>, and a second side 46b is adjacent to and in abutment with the second plate <NUM>. In the example, the first and second sides 46a, 46b abut and engage the first and second plates <NUM>, <NUM> without any additional sealing structure (e.g., gaskets or sealant) therebetween. A motor <NUM> is mounted to the first plate and rotationally drives a rotor <NUM> received in a bore <NUM> of the intermediate plate <NUM> via a shaft <NUM>.

In the example, the first, second, and intermediate plates <NUM>, <NUM>, <NUM> are 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 plates <NUM>, <NUM>, <NUM> include at least two locator holes <NUM> that are each configured to temporarily receive a through-pin during assembly of the pump <NUM> to precisely align the plates with one another. Fasteners <NUM> are received in fastener holes <NUM> in the first, second, and intermediate plates <NUM>, <NUM>, <NUM>. In the example, the ends <NUM> of the fasteners <NUM>, which may be metal, are plastically deformed to securely retain the first and second plates <NUM>, <NUM> in a clamping relationship about the intermediate plate <NUM>. Threaded fasteners, rivets or other types of fastening may also be used.

The example pump <NUM> is a rotary vane configuration. Referring to <FIG>, an elliptical bore <NUM> is illustrated. The rotor <NUM> includes multiple slots <NUM> about its circumference. The slots <NUM> slidably receive vanes <NUM> that are moveable within the slot to seal against the periphery of the bore <NUM> from centrifugal forces, as is known in rotary vane pumps. For the elliptical bore <NUM>, two cavities <NUM>, <NUM> are provided to create a two-chamber configuration that balances pressure across the rotor <NUM>.

Referring to <FIG>, the intermediate plate <NUM> is reversible such that either side 46a, 46b may mate with either the first and second plate <NUM>, <NUM>. That is, the intermediate plate <NUM> is symmetrical about an axis A such that first and second surfaces 72a, 72b respectively provided by the first and second sides 46a, 46b and their corresponding fluid passages are the same if rotated <NUM>° about the axis A. In one example, these surfaces 72a, 72b are 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 passage 74a on the first side 46a fluidly connects the inlet <NUM> to the bore <NUM>, as shown in <FIG> and <FIG>. The first passage 74a includes a first passageway 76a fluidly connected to the ambient side V of first cavity <NUM> and a second passageway 78a fluidly connected to the ambient side V the second cavity <NUM>. The pocket 68a is arranged in the first passage 74a fluidly between the inlet port <NUM> and the bore <NUM>.

In a similar manner, a second passage 74b on the second side 46b fluidly connects the outlet <NUM> to the bore <NUM>, as shown in <FIG>. The second passage 74b includes a first passageway 76b fluidly connected pressure side P of the second cavity <NUM> and a second passageway 78b fluidly connected to the pressure side P of the first cavity <NUM>. The pocket 68b is arranged in the second passage 74b fluidly between the outlet port <NUM> and the bore <NUM>.

At least one of the pockets 68a, 68b receives a filter <NUM> (e.g., foam), but both pockets 68a, 68b may include a filter <NUM> if desired. In this manner, contaminants are filtered from the system <NUM> and no external lines or fittings are needed as the internal filter is contained within the pump <NUM>. The LDM <NUM> does not require protection against ISO ultrafine dust (<NUM>-<NUM> 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 LDM <NUM> may 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 pump <NUM>.

Another rotary vane configuration is shown in <FIG>, which illustrates an intermediate plate <NUM> with a circular bore <NUM> having a single crecent-shaped cavity. In this example, the first side 146a and its first surface 172a have a first passage 174a fluidly connecting the pocket 68a to ambient side V of the bore <NUM>. The intermediate plate <NUM> is reversible. As shown in <FIG>, the second side 146b and its second surface 172b have a second passage 174b fluidly connecting the pocket 68b to pressure side P of the bore <NUM>.

During manufacturing of the pump, the first plate <NUM> is arranged into abutting engagement with either the first side 46a or the second side 46b of the intermediate plate <NUM>. That is, the intermediate plate is reversible with respect to the first and second plates <NUM>, <NUM>. The rotor <NUM> is disposed along with slidable vanes <NUM> into the bore <NUM>. The second plate <NUM> is arranged into abutting engagement with the other of the first and second sides 46a, 46b. The first and second plates <NUM>, <NUM> are secured about the intermediate plate <NUM> and rotor <NUM>. The motor <NUM> is mounted to the first plate <NUM>, coupling the motor <NUM> to the rotor <NUM>.

Claim 1:
A rotary vane pump (<NUM>) , which receives a fluid through an inlet port (<NUM>) and provides the pressurized fluid to an outlet port (<NUM>), comprising:
a housing (<NUM>) including first and second plates (<NUM>, <NUM>) respectively secured to first and second opposing sides (46a, 46b) of an intermediate plate (<NUM>);
wherein the intermediate plate (<NUM>) includes a bore (<NUM>) and the inlet and outlet ports (<NUM>, <NUM>), the first and second sides (46a, 46b) respectively having first and second passages (74a, 74b) that are respectively in fluid communication with the inlet and outlet ports (<NUM>, <NUM>), and the first and second passages (74a, 74b) are in fluid communication with the bore (<NUM>), wherein the intermediate plate (<NUM>) is reversible with respect to the first and second plates (<NUM>, <NUM>), such that either of the first and second sides (46a, 46b) may mate with either of the first and second plates (<NUM>, <NUM>); and
a rotor (<NUM>) arranged in the bore (<NUM>), the rotor (<NUM>) supporting slidable vanes (<NUM>) configured to pump the fluid between the inlet and outlet ports (<NUM>, <NUM>);
wherein the intermediate plate (<NUM>) is symmetrical about an axis (A) such that first and second surfaces (72a, 72b) respectively provided by the first and second sides (46a, 46b) and their corresponding first and second passages (74a, 74b) are the same if rotated <NUM>° about the axis (A).