Low viscosity vane pumps for evaporative emission systems

Abstract

This invention relates to a low-viscosity vane pump for an evaporative emission system, comprising a housing providing orifices in fluid communication with inlet and outlet channels, and a rotating assembly disposed within the orifices and configured to rotate relative to the orifices. The rotating assembly includes a rotor mounted on a shaft and having a plurality of slots. The rotor has a first face and a second face that engage with the housing. Vanes are received in each slot, each vane having a first surface and a second surface extending longitudinally from a first end to a second end. The first end is received in its respective slot. The rotating assembly includes recesses located on at least one of the first face, the second face, the first surface of the first end, and the second surface of the first end.

Description

Technical Field

[0001] This invention relates to vane pumps and evaporative discharge systems incorporating vane pumps. Background Technology

[0002] Evaporative emission systems have long been essential for gasoline-powered vehicles. These systems must undergo leak testing during vehicle startup to ensure that fuel vapors do not leak into the atmosphere. A pump is used to create a vacuum or pressurize the system. An external filter is used to prevent contamination that could damage the pump or other system components during operation. Several valves may be closed during this test procedure to maintain system pressure, and this pressure is monitored to determine if any leaks are present.

[0003] When a leak exists in the evaporation system at high ambient temperatures (>35°C), the gasoline vapors (VOCs) escaping through the leak exceed the design limits of a normally operating evaporation system. Within 24 hours, the amount of gas released from the vapor chamber of the fuel tank through a 1mm leak can exceed ten times the permissible amount for evaporation leaks. Therefore, there is a need for an evaporation emission system leak test that can quickly and accurately detect leaks in the system.

[0004] Vane pumps are designed so that the vanes extend outward from the centerline of their supporting rotor during operation, compressing air and causing it to flow through the pumping chamber. The vanes are typically oriented perpendicular to the drive shaft and slide within corresponding slots in the rotor, following the contour of the chamber wall as the vanes rotate. Existing technology uses rectangular vanes with smooth, uniform surfaces on all operating surfaces of the rotor and vanes. Summary of the Invention

[0005] In one example embodiment, a vane pump includes a housing providing an orifice in fluid communication with an inlet passage and an outlet passage, and a rotating assembly disposed within the orifice and configured to rotate relative to the orifice. The rotating assembly includes a rotor mounted on a shaft and having a plurality of slots. The rotor has a first facet and a second facet that engage with the housing. Vanes are received in each slot, each vane having a first surface and a second surface extending longitudinally from a first end to a second end. The first end is received in its respective slot. The rotating assembly includes a recess located on at least one of the first facet, the second facet, the first surface of the first portion, and the second surface of the first portion.

[0006] In any of the other embodiments described above, each blade comprises a substantially rectangular cross-section provided by spaced-out long sides combined with spaced-out short sides. The long sides are provided by a first surface and a second surface, and a recess is provided on at least one of the first surface and the second surface.

[0007] In any of the other embodiments described above, the short side extends a first width in the thickness direction transverse to the longitudinal direction, the long side extends in the height direction transverse to the longitudinal direction and the thickness direction, and the recess has a second width in the thickness direction that is less than the first width.

[0008] In any of the other embodiments described above, the trough has a trough width, a trough height, and a trough depth. The first width is substantially equal to the trough width, and a first portion such that the first width is at least partially contained within the trough depth during operation of the vane pump.

[0009] In any of the other embodiments described above, a plurality of recesses are provided on each blade.

[0010] In any of the other embodiments described above, at least one recess is provided on each of the first face and the second face.

[0011] In any of the other embodiments described above, the recess extends to the end of the second portion.

[0012] In any of the other embodiments described above, the recess is provided on at least one of the first face and the second face.

[0013] In any of the other embodiments described above, the first face and the second face are each bounded by an outer periphery, and the recess is completely contained within the outer periphery.

[0014] In any of the other embodiments described above, the rotor and blades are made of plastic, and the recesses are defined by molded surfaces.

[0015] In any of the other embodiments described above, the vane pump includes a motor connected to a rotating assembly via a shaft.

[0016] In another example embodiment, an evaporative emission system including the vane pump includes a fuel system having a fuel tank and a carbon canister, the fuel system containing steam. At least one valve is positioned in a closed position during a leak detection procedure. The vane pump includes a motor connected to a rotating assembly via a shaft. A controller is in communication with the pump and is configured to maintain pressure on the system with the vane pump during a leak test procedure. The rotating assembly is configured to collect steam in a recess during operation.

[0017] In any of the other embodiments described above, each blade comprises a substantially rectangular cross-section provided by spaced-out long sides joining spaced-out short sides. The long sides are provided by a first surface and a second surface, and a recess is provided on at least one of the first surface and the second surface.

[0018] In any of the other embodiments described above, the short side extends a first width in the thickness direction transverse to the longitudinal direction, and the long side extends in the height direction transverse to both the longitudinal and thickness directions. The recess has a second width in the thickness direction that is less than the first width. The groove has a groove width, a groove height, and a groove depth. The first width is substantially equal to the groove width, and a first portion such that the first width is at least partially contained within the groove depth during operation of the vane pump.

[0019] In any of the other embodiments described above, the recess is provided on at least one of the first face and the second face. Attached Figure Description

[0020] The invention can be further understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0021] Figure 1A The illustration shows a portion of an example evaporative fuel system.

[0022] Figure 1B It is used for Figure 1A The diagram shows a leak detection module (LDM) for the system.

[0023] Figure 2A This is a 3D view of an example rotary vane pump.

[0024] Figure 2B It is intercepted along line 2B-2B. Figure 2A A cross-sectional view of the pump.

[0025] Figure 3A The image shows a front view of the pump with the first plate removed, exposing the rotor in the middle plate.

[0026] Figure 3B This is a 3D view of the middle plate with the filter installed.

[0027] Figure 4A and 4B They are Figure 3B The first and second perspective views of the intermediate plate are shown.

[0028] Figure 5 This is a top view of the rotor.

[0029] Figure 6 This is a side view of the blade broken off.

[0030] Figure 7A This is a side view of another example blade.

[0031] Figure 7B yes Figure 7A The end view of the blade shown.

[0032] The embodiments, examples, and alternatives described in the foregoing paragraphs, claims, or the following description and drawings, including their different aspects or corresponding independent features, can be considered individually or in any combination. Features described in connection with one embodiment apply to all embodiments unless those features do not match. Corresponding reference numerals and names in different drawings denote the same elements. Detailed Implementation

[0033] Figure 1A A portion of an example evaporative fuel system 10 is schematically shown. System 10 includes a fuel tank 12 with a fuel filler 14 having a filler cap 16. A fuel pump 18 supplies gasoline, for example, from the fuel tank 12 to an internal combustion engine 20. A fuel level sensor 15 communicates with a controller 40 and measures the fuel level in the fuel tank 12, which is also correlated with the amount of fuel vapor in the fuel tank 12.

[0034] System 10 is configured to capture and regulate fuel vapor flow within the system. In one example, a fuel tank isolation valve 24 is fluidly disposed between the fuel tank 12 and a carbon canister 22 that captures and stores fuel vapor for subsequent use by the engine 20. A purge valve 26 is fluidly connected between the carbon canister 22 and the engine 20. Controller 40 adjusts the position of the purge valve 26 to selectively supply fuel vapor to the engine 20 for utilization during operation.

[0035] System 10 must be periodically tested for integrity to ensure no fuel vapor leaks from it. One type of system 10 uses a leak detection module (LDM) 28, which can be used to evacuate and / or pressurize the system, thereby using, for example, a pressure sensor 53 to determine if a leak is present. In an example leak test procedure, purge valve 26 is closed and controller 40 operates leak detection module 28 to evacuate or pressurize the system. Another pressure sensor 51 can be used to monitor the pressure of fuel vapor within fuel tank 12 during other conditions. An optional ambient temperature sensor 55 communicates with controller 40. Temperature sensor 55 can help quantify the heat transfer characteristics of fuel vapor within fuel tank 12 relative to the ambient atmospheric temperature.

[0036] LDM28 in Figure 1BThe diagram is schematically shown. The LDM28 includes a pump 30 housed within a casing. An example pump is disclosed in U.S. Application No. 17 / 765,628, filed March 31, 2022, entitled "Pump for Evaporative Emission Systems," which is incorporated herein by reference in its entirety. Some consumers prefer systems that operate under vacuum, while others prefer pressurized systems. Therefore, to provide a pressurized vapor emission system test, the pump 30 draws air from the atmosphere through a filter 32 and directs that air toward the carbon canister 22. Another filter 34 may be disposed on the other side of the pump 30 to protect the pump from debris. To provide a depressurized or negative pressure vapor emission system test (i.e., vacuum), the pump 30 draws air from the carbon canister 22 and vents it to the atmosphere. An example leak detection method is disclosed in U.S. Application No. 18 / 023,523, filed February 27, 2023, entitled "Entropy Method for Leak Detection Module for Evaporative Emission Systems," which is incorporated herein by reference in its entirety.

[0037] In one example, when LDM28 is not performing leak detection on fuel system 10, the carbon canister valve solenoid (CVS) 31 is in the open position to allow air to pass through the first fluid passage 61 between the remainder of system 10 and the atmosphere. This allows system 10 to draw air from the atmosphere as needed.

[0038] When LDM28 performs a leak test on fuel system 10, CVS31 is in the closed position, which provides a second fluid passage 63 on the side of the carbon canister 22. A CVS check valve 33 is located in the second fluid passage 63 and selectively isolates the carbon canister 22 from pump 30 and the atmosphere. Pressure sensor 53 is configured to read the pressure in the second fluid passage 63 when CVS31 is closed, but the pressure sensor can also be used for other purposes.

[0039] LDM28 includes the hardware necessary to determine whether system 10 is leaking to the atmosphere. During a leak test, pump 30 is separated from the volume of air being checked for leaks, depending on how the CVS check valve 33 is used. Pump 30 can generate negative (vacuum) or positive pressure in the evaporative exhaust system, depending on its direction of rotation, as described above. The leak boundaries of system 10 include the fuel filler 14 and cap 16, purge valve 26, the fresh air side of carbon canister 22 (the side connected to LDM28), the vapor chamber of fuel tank 12, and the vapor lines connecting all components (including the second fluid passage 63).

[0040] During a leak test, pressure sensor 53 is in fluid communication with a second fluid passage 63 and monitors the pressure generated in system 10 by pump 60. Pressure sensor 53 communicates with controller 40, which determines whether there are pressure changes in the evaporative emission system within a predetermined time period that may indicate a leak. Any pressure changes detected by pressure sensor 53 and monitored by controller 40 indicate a leak. OBDII diagnostic system 41 communicates with controller 40 and uses the pressure information from the pressure sensor to generate an engine fault code, which can be stored and used to illuminate a "Check Engine" light on the vehicle dashboard indicating that vehicle maintenance is required. An example diagnostic system is disclosed in U.S. Application No. 17 / 882,055, filed August 5, 2022, entitled "Evaporative Emission Leak Detection Module with Integrated Control and Communication Systems," which is incorporated herein by reference in its entirety.

[0041] The controller 40 and the OBDII system 41 can be integrated or separate. In terms of hardware architecture, such a controller may include a processor, memory, and one or more input and / or output (I / O) device interfaces communicatively coupled via a local interface. The local interface may include, for example, but not limited to, one or more buses and / or other wired (e.g., CAN, LIN, and / or LAN) or wireless connectors. The local interface may have additional components omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communication. Furthermore, the local interface may include address, control, and / or data connectors to enable proper communication between the aforementioned components.

[0042] A controller can be a hardware device used to execute software, particularly software stored in memory. A processor can be a custom or commercially available processor, a central processing unit (CPU), an auxiliary processor associated with the controller among multiple processors, a microprocessor-based semiconductor (in the form of a microchip or chipset), or in general any device used to execute software instructions.

[0043] The memory may include any or a combination of volatile storage elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, VRAM, etc.)) and / or non-volatile storage elements (e.g., ROM, etc.). Furthermore, the memory may include electronic, magnetic, optical, and / or other types of storage media. The memory may also have a distributed architecture, where multiple components are geographically separated but accessible through a controller.

[0044] Software in memory may include one or more individual programs, each comprising an ordered list of executable instructions for implementing logical functions. System components implemented as software can also be understood as source programs, executable programs (object code), scripts, or any other entity containing a set of instructions to be executed. When constructed as a source program, the program is translated by a compiler, assembler, interpreter, etc., which may or may not be contained in memory.

[0045] When the controller operates, the processor can be configured to execute software stored in memory to transfer data to and from memory, and to control the operation of the computing device overall, based on the software. The software in memory is read, in whole or in part, by the processor, may be buffered within the processor, and then executed.

[0046] exist Figure 2A An example leak detection module 28 is shown in more detail below. Module 28 includes a pump 30 that receives atmospheric air through an inlet port 34. The pump supplies pressurized air to an outlet port 36, which can be supplied to the carbon canister 22 or other evaporation components of the system 10 via a check valve 33.

[0047] Pump 30 has a housing 40 consisting of a first plate 42 and a second plate 44 fixed to both sides of an intermediate plate 46. It should be understood that pump 30 can be constructed in a manner different from the disclosed one. For example, the intermediate plate may not be used. In the example described, the inlet port 34 and the outlet port 36 are located on the edge of the intermediate plate 46, rather than on one or both of the first plate 42 and the second plate 44. (See reference) Figure 2A and 2B The intermediate plate 46 has a first side 46a that abuts against the first plate 42 and a second side 46b that abuts against the second plate 44. In this example, the first side 46a and the second side 46b abut against and engage the first plate 42 and the second plate 44. A motor 48 is mounted on the first plate and rotatably drives a rotor 52 received in a hole 62 in the intermediate plate 46 via a shaft 50. The rotor 52 includes a hole 90 for keying the rotor 52 to the shaft 50. Figure 5 ).

[0048] In this example, the first plate 42, the second plate 44, and the intermediate plate 46 are made of a plastic material, such as nylon or polypropylene, which may be filled with graphite or Teflon. In one example, the plastic is injection molded, providing surfaces with characteristics that identify and indicate the molding process (e.g., shrinkage lines and streamlines). Plates 42, 44, and 46 include at least two positioning holes 54, each configured to temporarily receive a through pin during assembly of the pump 30 to ensure accurate alignment of the plates with each other. Fasteners 56 are received in fastening holes 58 in the first plate 42, the second plate 44, and the intermediate plate 46. In this example, the ends (which may be metallic) of the fasteners 56 undergo plastic deformation to securely hold the first plate 42 and the second plate 44 in a clamped relationship around the intermediate plate 46. Threaded fasteners, rivets, or other types of fasteners may also be used.

[0049] Example pump 30 is a rotary vane construction. (Reference) Figure 3A and 3B An elliptical bore 62 is shown. However, a circular bore with an offset rotor can be used alternatively if needed. The rotor 52 includes a plurality of slots 64 around its circumference. The slots 64 slidably receive blades 66 that can move within the slots to seal the outer periphery of the bore 62, thereby protecting it from centrifugal forces, as is known in rotary vane pumps. For the elliptical bore 62, two chambers 80, 82 are provided to form a dual-chamber configuration that balances the pressure on the rotor 52.

[0050] The channel 74a on the first side 46a fluidly connects the inlet 34 to the orifice 62, such as Figure 3A and 4A As shown. The first channel 74a includes a first passage 76a fluidly connected to the environmental side V of the first cavity 80 and a second passage 78a fluidly connected to the environmental side V of the second cavity 82. A socket 68a is fluidly disposed in the first channel 74a between the inlet port 34 and the hole 62.

[0051] In a similar manner, the second channel 74b on the second side 46b fluidly connects the outlet 36 to the orifice 62, as... Figure 4B As shown. The second channel 74b includes a second passage 76b fluidly connected to the pressure side P of the second cavity 82 and a second passage 78b fluidly connected to the pressure side P of the first cavity 80. A socket 68b is fluidly disposed in the second channel 74b between the outlet port 36 and the hole 62.

[0052] At least one of the sockets 68a and 68b receives a filter 32 (e.g., foam), but both sockets 68a and 68b may include a filter 32 if necessary. In this way, contaminants are filtered from system 10, and no external piping or fittings are required due to the inclusion of an internal filter within pump 30. LDM28 does not require protection against ISO ultrafine dust (1-22 microns) because it does not have the calibration orifice found in some types of leak-detection pumps. The type of foam filter element that can be included in LDM28 may not prevent ultrafine dust from entering the pump assembly. Instead, this is not a risk to pump performance because the dust concentration is relatively low relative to the volume of air passing through pump 30.

[0053] Pumps designed to move fluids rely on the lubrication of the material being pumped. Since air pumps do not have a liquid to lubricate rotating parts during blade extension, they rely on centrifugal force to extend the blades. Condensation in a vane pump, such as in fuel system 10, can cause sticking of rotating and sliding parts due to adhesion between two wetted surfaces. The disclosed vane pump reduces sticking in the presence of steam by providing one or more channels or recesses along the outlet path of the blades that allow condensate buildup and / or due to centrifugal force generated during rotation.

[0054] Pump 30 includes a housing provided by one or more plates 42, 44, 46 as described above. Orifice 62 is in fluid communication with inlet and outlet passages (e.g., channels 74a, 74b). These passages can be configured in any suitable manner to supply air to and from fuel system 10.

[0055] A rotating assembly comprising a rotor 52 and blades 66 is disposed within and configured to rotate relative to the bore 62. A circumferentially arranged volume is provided between adjacent blades 66, forming a chamber that changes size during rotation to generate a pressure differential on the pump 30. As the rotating assembly is driven by a motor 48, centrifugal force causes each blade 66 to slide radially outward relative to its corresponding slot 64 to seal against the outer peripheral wall of the bore 62. Since each blade 66 must slide rapidly in and out of its slot during rotation, any viscous movement that prevents this sliding motion will prevent the blades 66 from sealing, thus preventing the pump 30 from reaching its required pressure.

[0056] To reduce the effects of viscosity (especially in the presence of steam), one or more recesses are provided at the junction of rotation and / or sliding in the rotating assembly. However, the recesses are configured to prevent pressurized air from leaking from the high-pressure chamber to the low-pressure chamber across the rotor 52 or blades 66.

[0057] Rotor 52 has a first face 98 and a second face 100 that are opposite each other. Figure 5 and 7AThese components engage and rotate relative to the housing during operation. To reduce adhesion between the rotor 52 and the housing, at least one recess 102 is provided on at least one of the first face 98 and the second face 100. In this example, multiple L-shaped recesses are provided. The first face 98 and the second face 100 are each bounded by an outer periphery 96 (dashed line), and the recess 102 is completely contained within the outer periphery 96. This better prevents leakage from one chamber to another.

[0058] Example blades 66 and 166 are in Figure 6-7B The blade 66 is shown and generally referred to as "blade 66". Each blade 66 has a substantially rectangular cross-section provided by spaced-apart long sides 108, 110 joining spaced-apart short sides 112, 114. The long sides 108, 110 are provided by a first surface 104 and a second surface 106. The short sides 112, 114 extend a first width 124 in the thickness direction T transverse to the longitudinal direction L. The long sides 108, 110 extend a height 128 in the height direction H transverse to both the longitudinal direction L and the thickness direction T. The groove 66 has a groove width 92, a groove height 94, and a groove depth 95. The first width 124 is substantially equal to the groove width 92, and a first portion 118 such that the first width 124 is at least partially contained within the groove depth 95 during operation of the pump 30. Using the recess 122 of the present invention, the contact at the junction between the first portion 118 and the groove 64 is reduced by about 50% in one example.

[0059] Each blade 66, received in a corresponding slot 66, extends in the longitudinal direction L from a first end 118 to a second end 120. The first end 118 is received in its corresponding slot 66, and the second end 120 has an end 116 that engages with the outer peripheral wall of the hole 62.

[0060] To reduce adhesion between the blade 66 and the rotor slot 64, one or more recesses 122 are provided on at least one of the first surface 104 and the second surface 106. The recess 122 has a second width 126 in the thickness direction T, providing an effective depth for collecting any condensed vapor. The second width 126, corresponding to the thickness of the blade 66 at the recess 122, is smaller than the first width 124. In this example, the recess 122 extends to the end 116 of the second portion 120. Centrifugal force concentrates liquid from the interface between the rotor 52 and the first portion 118 of the blade 66, allowing it to be discharged from these mating surfaces to the end 116 and exit the pump outlet. A wall 130, having a first width 124 and extending the entire height 128 of the blade 66 in the height direction H, prevents leakage across the blade within the slot 64.

[0061] In the example described, rotor 52 and blades 66 are constructed of a plastic material suitable for the application. In one example, recesses 102 and 122 are defined by molded surfaces that are structurally identifiable and distinct from other types of surfaces (e.g., machined surfaces). Coatings can be added to recesses 102 and / or 122 as needed to enhance liquid shedding from the surface. The geometry of recesses 102 and 122 can vary depending on the materials used, pump speed, pressure, and application.

[0062] During operation, the controller 40 communicates with the pump 30 to maintain pressure on the system. The evaporative discharge system 10 operates with virtually no viscous pump 30, enabling the pump 30 to reach the pressure required for leak testing.

[0063] It should also be understood that although a particular arrangement of components is disclosed in the illustrated embodiment, other arrangements will also benefit from it. Although a particular sequence of steps has been shown, described, and claimed, it should be understood that, unless otherwise stated, these steps may be performed in any order, may be performed separately or in combination, and will still benefit from the invention.

[0064] Although the different examples have the specific components shown in the figures, embodiments of the invention are not limited to these specific combinations. Some components or features of one example may be used in combination with features or components of another example.

[0065] Although exemplary embodiments have been disclosed, those skilled in the art will recognize that certain modifications will fall within the scope of the claims. Therefore, the appended claims should be examined to determine their true scope and content.

Claims

1. A vane pump, comprising: The housing provides openings that are in fluid communication with the inlet and outlet channels; A rotating component disposed within the hole and configured to rotate relative to the hole. The rotating component includes: A rotor mounted on a shaft and having multiple slots, the rotor having a first face and a second face that engage with the housing; A blade is received in each slot, each blade having a first surface and a second surface extending longitudinally from a first end to a second end, the first end being received in its respective slot, and The rotating component includes a recess disposed on at least one of the first face and the second face.

2. The vane pump according to claim 1, wherein, The first face and the second face each have an outer periphery as their boundary, and the recess is completely contained within the outer periphery.

3. A vane pump, comprising: The housing provides openings that are in fluid communication with the inlet and outlet channels; A rotating component disposed within the hole and configured to rotate relative to the hole. The rotating component includes: A rotor mounted on a shaft and having multiple slots, the rotor having a first face and a second face that engage with the housing; A blade is received in each slot, each blade having a first surface and a second surface extending longitudinally from a first end to a second end, the first end being received in its respective slot, and The rotating assembly includes a recess disposed on at least one of a first surface and a second surface of the first end portion, wherein each blade includes a substantially rectangular cross-section provided by spaced-apart long sides combined with spaced-apart short sides, the long sides being provided by the first and second surfaces, and the recess is disposed on at least one of the first and second surfaces, wherein the short sides extend a first width in a thickness direction transverse to the longitudinal direction, the long sides extend in a height direction transverse to both the longitudinal and thickness directions, and the recess has a second width in the thickness direction less than the first width, and the first end portion includes a wall received in the groove having a full first width extending over the entire height of the blade to prevent leakage across the blade within the groove. The groove has a groove width, a groove height, and a groove depth, the first width being substantially equal to the groove width, and the first end portion such that the first width is at least partially contained within the groove depth during operation of the vane pump.

4. The vane pump according to claim 3, wherein, At least one recess is provided on each of the first surface and the second surface.

5. The vane pump according to claim 3, wherein, The rotor and the blades are made of plastic, and the plurality of recesses are defined by a molded surface.

6. The vane pump of claim 3, further comprising a motor connected to the rotating assembly via the shaft.

7. An evaporative discharge system comprising the vane pump according to claim 3, comprising: A fuel system comprising a fuel tank and a carbon canister, the fuel system containing steam; At least one valve is set in the closed position during a leak detection procedure; The vane pump includes a motor connected to a rotating assembly via a shaft; and A controller that communicates with the pump is configured to maintain pressure on the system having the vane pump during a leak test procedure, and the rotating assembly is configured to collect steam in the recess during operation.

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