Leak detection module and evaporative emission system

Abstract

The utility model relates to a leakage detection module and an evaporative emission system. The leak detection module includes a housing positioned between the canister and the atmosphere and including a first port that fluidly communicates the housing to the canister and a second port that fluidly communicates the housing to the atmosphere; a canister valve solenoid disposed within the housing and in fluid communication along the first fluid passage between the first port and the second port, and movable between open and closed positions; a pump disposed within the housing and in fluid communication along a second fluid passage between the first port and the second port, where the first fluid passage and the second fluid passage are parallel to each other; and a fuel tank isolation valve system facilitating fluid flow between the canister and the atmosphere, disposed within the housing between the first port and the first fluid passage and between the first port and the second fluid passage, and in fluid communication with the first port, the first fluid passage, and the second fluid passage.

Description

Technical Field

[0001] The utility model relates to a leak detection module (LDM) for an evaporative emission system and an evaporative emission system. Background Art

[0002] For a long time, gasoline-powered vehicles have always required an evaporative emission system. This system must be regularly leak-tested during or after a vehicle driving cycle to ensure that fuel vapor does not leak into the atmosphere. In this test procedure, various valves can be closed to maintain the system pressure, and the pressure is monitored to determine whether any leaks exist.

[0003] One type of evaporative emission system uses a leak detection module (LDM), which typically houses a pump and one or more valves in a common housing for performing leak tests. In addition, a fuel tank isolation valve is used to selectively block the flow of fuel vapor from the fuel tank. Summary of the Utility Model

[0004] In some aspects, the technology described in the utility model relates to a leak detection module, which includes: a housing, wherein the housing is positioned between the charcoal canister and the atmosphere, and the housing includes a first port that fluidly connects the housing to the canister and a second port that fluidly connects the housing to the atmosphere; a canister valve solenoid, the canister valve solenoid is arranged in the housing and is fluidly connected along a first fluid passage between the first port and the second port, and the canister valve solenoid can move between an open position and a closed position; a pump, the pump is arranged in the housing and is fluidly connected along a second fluid passage between the first port and the second port, wherein the first fluid passage and the second fluid passage are parallel to each other; a fuel tank isolation valve system, the fuel tank isolation valve system is used to facilitate the fluid flow between the canister and the atmosphere, wherein the fuel tank isolation valve system is arranged in the housing between the first port and the first fluid passage and between the first port and the second fluid passage, and the fuel tank isolation valve system is fluidly connected to the first port, the first fluid passage and the second fluid passage, the fuel tank isolation valve system further includes a first chamber, a second chamber and a third chamber, the first chamber, the second chamber and the third chamber together define a plurality of fluid paths through the fuel tank isolation valve system, the fuel tank isolation valve system further includes a solenoid valve and a mechanical bypass system, wherein the solenoid valve is electrically controlled to open and close and regulates the conveyance of fluid through a first fluid path among the plurality of fluid paths, and the mechanical bypass system automatically responds to a positive pressure difference or a negative pressure difference across the chambers and regulates the conveyance of fluid through a second fluid path among the plurality of paths.

[0005] In some aspects, the technology described by the present utility model relates to a module, wherein the first chamber is positioned between the first port and the second chamber, the second chamber is positioned between the first chamber and the third chamber, and the third chamber is positioned between the second chamber and the first fluid passage and between the second chamber and the second fluid passage.

[0006] In some aspects, the technology described by the present utility model relates to a module, wherein the first fluid path conveys fluid between the first chamber and the third chamber.

[0007] In some aspects, the technology described by the present utility model relates to a module, wherein the second fluid path conveys fluid from the first chamber to the second chamber, to the third chamber, and also from the third chamber to the second chamber, to the first chamber.

[0008] In some aspects, the technology described by the present utility model relates to a module, wherein a release hole between the first chamber and the second chamber fluidly connects the first chamber and the second chamber.

[0009] In some aspects, the technology described by the present utility model relates to a module, wherein a pressure reducing valve is positioned between the second chamber and the third chamber to control the conveyance of fluid flowing in the direction from the first port to the second port.

[0010] In some aspects, the technology described by the present utility model relates to a module, wherein an air supply spring is positioned between the second chamber and the third chamber to control the conveyance of fluid flowing in the direction from the second port to the first port.

[0011] In some aspects, the technology described by the present utility model relates to an evaporative emission system including the above leak detection module, the system comprising: an engine configured to provide vehicle propulsion; a fuel tank configured to contain fuel and fuel vapor selectively supplied to the engine; the above charcoal canister configured to store the fuel vapor from the fuel tank; a purge valve fluidly connected to the charcoal canister and configured to selectively supply the fuel vapor to the engine in response to a purge command.

[0012] In some aspects, the technology described by the present utility model relates to a leak detection module, which includes: a housing, wherein the housing is positioned between the charcoal canister and the atmosphere, and the housing includes a first port fluidly connecting the housing to the canister and a second port fluidly connecting the housing to the atmosphere; a canister valve solenoid, which is arranged inside the housing and is fluidly connected between the first port and the second port along a first fluid passage, and the canister valve solenoid is electrically controlled by a controller to move between an open position and a closed position; a pump, which is arranged inside the housing and is fluidly connected to the first port and the second port along a second passage between the first port and the second port, wherein the first fluid passage and the second fluid passage are parallel to each other; an umbrella check valve, which is arranged inside the housing and is fluidly connected along the second passage between the first port and the pump, wherein the umbrella check valve is a one-way mechanical valve configured to transfer fluid flow along the second passage from the second port to the first port and prevent fluid from being transferred along the second passage from the first port to the second port; a pressure sensor, which is fluidly connected to at least one of the first port and the second port.

[0013] In some aspects, the technology described by the present utility model relates to a leak detection module, wherein the umbrella check valve includes a rod fixed to a convex sealing disc.

[0014] In some aspects, the technology described by the present utility model relates to a leak detection module, wherein the second passage includes a seat perpendicular to the second passage and positioned across the second passage, and the seat is configured to receive the umbrella check valve.

[0015] In some aspects, the technology described by the present utility model relates to a leak detection module, wherein the seat receives the umbrella check valve such that the rod protrudes through the first side of the seat, and the sealing disc is pressed flush with the opposite second side of the seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present utility model can be further understood by referring to the following detailed description when considered in conjunction with the accompanying drawings, wherein:

[0017] Figure 1 Part of an exemplary evaporative emission system is schematically shown.

[0018] Figure 2 is Figure 1 a schematic diagram of a leak detection module (LDM) of the evaporative emission system shown.

[0019] Figure 3 is a cross-sectional view of the LDM for Figure 1 the evaporative emission system shown.

[0020] Figure 4 Schematically shows a portion of a second exemplary evaporative emission system.

[0021] Figure 5 is for Figure 4 Schematic diagram of the LDM of the evaporative emission system shown.

[0022] Figure 6 is a view showing for Figure 4 Computer-aided design (CAD) drawing of a perspective view of the LDM of the evaporative emission system shown.

[0023] Figure 7 is a view showing for Figure 4 CAD drawing of a cross-sectional view of the fuel tank isolation valve (FTIV) system of the LDM of the evaporative emission system shown.

[0024] Figure 8 is a view showing Figure 4 CAD drawing of a cross-section of the mechanical bypass system of the FTIV system of the evaporative emission system shown.

[0025] Any one of the foregoing paragraphs, claims, or embodiments, examples, and alternatives of the following description and drawings, including each aspect or their respective individual features, can be obtained independently or in any combination. Features described in connection with one embodiment apply to all embodiments unless they are incompatible. The same reference numerals and labels in the various drawings denote the same elements. Detailed Description

[0026] Figure 1 Schematically shows a portion of an exemplary evaporative fuel system 10. It should be understood that other types of systems can be used, such as Figure 4 the system shown. For Figures 1 to 8 each of the evaporative emission systems shown, the evaporative emission system 10 includes a fuel tank 12 having a fuel filler opening 14 with a filler cap 16. In addition, a fuel pump 18 supplies gasoline, for example, from the fuel tank 12 to an internal combustion engine 20 that provides propulsion for a vehicle. Further, the evaporative emission system 10 includes a fuel level sensor 15 in communication with a controller 40, which can be an engine controller, that measures the fuel level within the fuel tank 12, which is also related to the amount of fuel vapor within the fuel tank 12.

[0027] The evaporative emission system 10 is configured to capture and regulate the fuel vapor flow within the system. In Figures 1 to 3In the example shown, the Fuel Tank Isolation Valve (FTIV) system 24 is a solenoid valve fluidly arranged between the fuel tank 12 and the charcoal canister 22. In this arrangement, the main function of the FTIV system 24 is to control the fuel vapor flow between the fuel tank 12 and the charcoal canister 22.

[0028] The FTIV system 24 can be opened either electrically or through a mechanical bypass. Whether the FTIV system 24 is open or closed depends on the operating conditions of the vehicle and the ambient temperature. For example, during normal operation of the vehicle, when the engine 20 of the vehicle is running, the FTIV system 24 remains open, allowing the fuel vapor generated in the fuel tank due to heat and fuel agitation to be drawn into the charcoal canister 22. Figures 1 to 3 In the example shown, when the engine 20 of the vehicle is turned off, the FTIV system 24 is typically closed and blocks the vapor flow between the fuel tank 12 and the charcoal canister 22.

[0029] The purge valve 26 is fluidly connected between the charcoal canister 22 and the engine 20. In one example, the controller 40 adjusts the position of the purge valve 26 in response to a purge command from the engine controller 40 during engine operation, for example, to selectively supply fuel vapor to the engine 20 during fuel combustion to utilize these fuel vapors.

[0030] The integrity of the evaporative emission system 10 must be tested regularly to ensure that there are no fuel vapor leaks. One type of evaporative emission system 10 uses a Leak Detection Module (LDM) 28, which can be used to evacuate and / or pressurize the system to determine if there are leaks, for example, using a pressure sensor 52. In an example leak test procedure, the purge valve 26 is closed and the LDM controller 44 operates the leak detection module 28 to evacuate or pressurize the system. Another pressure sensor 50 can be used to monitor the pressure of the fuel vapor inside the fuel tank 12 under other conditions.

[0031] An optional ambient temperature sensor communicates with the LDM controller 44. In one example, the temperature sensor 48 is arranged inside the housing 46 and is in fluid communication with at least one of the first port 64 and the second port 66. In another example, the temperature sensor 54 is arranged outside the LDM 28. The temperature sensor 48 can be used to quantify the heat transfer characteristics of the fuel vapor inside the fuel tank 12 relative to the ambient atmospheric temperature.

[0032] The LDM 28 has its own LDM controller 44, which is separate and unconnected from the engine controller 40. The controllers 40, 44 are arranged in separate housings remote from each other. Typically, the engine controller 40 is arranged at or near the engine compartment of the vehicle, while the LDM controller is arranged near the fuel tank 12 and / or the charcoal canister 22, which is typically at the rear of the vehicle. By using a separate LDM controller 44, the calculations and control algorithms for leak diagnosis can be performed external to the engine controller 40, which can greatly simplify the programming and I / O hardware of the engine controller. For example, instead of using eight wires from the LDM 28 to the engine controller 40, only two wires (i.e., two CAN bus wires; see Figure 2 68 in

[0033] Figure 2 Figure 2 can be used between the engine controller 40 and the LDM controller 44). Additionally, when using a separate LDM controller 44, the total power consumption during the leak test procedure can be reduced. Figure 2 As shown, the CVS fluid channel 60 and the pump fluid channel 62 are laid out in parallel with each other, and both of these channels 60, 62 are arranged between the first port 64 and the second port 66 to converge at the first port 64 and the second port 66. In another example, the LDM 28 can include an additional fluid channel having a pressure relief valve, where the additional fluid channel is laid out in parallel with the CVS fluid channel 60 and the pump fluid channel 62.

[0034] The LDM 28 includes a canister valve solenoid (CVS) 36. The CVS 36 is arranged within the LDM housing 46 and is in fluid communication along the CVS fluid channel 60 between the first port 64 and the second port 66. When the LDM 28 is not performing a leak test on the fuel system 10, the canister valve solenoid (CVS) 36 is in the open position to allow air to pass through the CVS fluid channel 60 between the rest of the system 10 and the atmosphere. This enables the system 10 to draw air from the atmosphere through the second port 66 as needed.

[0035] The LDM 28 includes a pump 30 disposed in a housing and positioned along a pump fluid passage 62. An example pump 30 is disclosed in the provisional application serial number 62 / 910,708, titled "Pump for Evaporative Emission System", filed on October 4, 2019, the entire content of which is incorporated herein by reference. A check valve 38 is disposed in the pump fluid passage 62 and selectively blocks the canister 22 from the pump 30 and the atmosphere via a second port 66. The pump 30 is arranged to be in fluid communication along the pump fluid passage 62 between the check valve 38 and the second port 66. The CVS fluid passage 60 and the pump fluid passage 62 are parallel to each other, and a pressure sensor 52 is in fluid communication with at least one of the CVS fluid passage 60, the pump fluid passage 62, the first port 64, and the second port 66. The pressure sensor 52 is arranged to read the pressure in the pump fluid passage 62 when the CVS 36 is closed, but the pressure sensor 52 can be used for other purposes.

[0036] As Figure 2 Best shown in, the LDM 28 includes a housing 46 for encapsulating an LDM controller 44, a pump 30, a CVS 36, a check valve 38, and a pressure sensor 52. The first port 64 and the second port 66 are provided by the housing 46. An electrical connector 68 is also provided by the housing 46. The electrical connector 68 may include three pins: one pin is connected to the positive pole of the power supply, and two pins are respectively connected to the negative poles of the CVS 36 and the pump 30. The engine controller 40 controls the on and off functions of the negative poles.

[0037] In one example of the LDM 28, as Figure 3 shown, the check valve 38 is an umbrella valve instead of a second solenoid. Therefore, Figure 3 the example shown includes a single canister valve solenoid 36 and a single umbrella valve. The umbrella valve is a one-way mechanical valve that operates automatically without an external control mechanism such as the LDM controller 44. The umbrella valve responds to changes in the pressure difference to allow or block the flow of air. The umbrella valve has an elastic sealing disk 55 that is convex / umbrella-shaped and fixed to a rod 56. The rod 56 and the sealing disk 55 are received by a valve seat 57 such that the rod 56 protrudes through the first side of the seat 57 and the sealing disk 55 is pressed flush with the opposite second side of the seat 57. The sealing disk 55 of the umbrella valve is configured to pivot between an open position and a closed position. Specifically, as Figure 3 shown, the umbrella valve is configured to allow pressurized air to flow from the second port 66 to the first port 64, but block the air from flowing in the opposite direction from the first port 64 to the second port 66. Therefore, when the pressure difference causes air to flow from the atmosphere to the canister 22, the umbrella valve opens and the sealing disk 55 separates from the seat 57. In addition, when the pressure difference causes air to flow from the canister 22 in the direction towards the pump 30, the umbrella valve closes and the convex sealing disk 55 contacts the seat 57 and forms a seal.

[0038] As shown Figure 3 in the example of the LDM 28 including the umbrella valve as the check valve 38, there are four operating modes. The four operating modes include a refueling mode, a purge mode, a pressurization mode, and a leak diagnosis mode. When the LDM 28 executes the refueling mode and the purge mode, the pump 30 is closed and the CVS 36 is opened. During refueling of the fuel tank 12, the pressure in the evaporative emission system 10 increases, and the open CVS 36 allows excess fuel vapor from the evaporative emission system 10 to be discharged to the atmosphere through the CVS fluid passage 60 from the second port 66. If the pressure sensors 50, 52 detect that the negative pressure difference between the evaporative emission system 10 and the atmosphere exceeds a stored threshold, the LDM 28 enters the purge mode. During the purge mode, air from the atmosphere flows into the LDM 28 through the second port 66. This air guided by the open CVS 36 through the CVS fluid passage 60 then leaves the LDM 28 through the first port 64 and reaches the canister 22.

[0039] The LDM 28 executes the pressurization mode and the leak diagnosis mode during a leak test. The leak test requires bringing the evaporative emission system 10 to a target pressure, closing off the evaporative emission system 10 to the atmosphere, and the pressure sensors 50, 52 measuring the pressure change over a period of time, where the controllers 40, 44 compare these measurements with stored thresholds. To start the leak test, the LDM 28 operates in its pressurization mode to bring the evaporative emission system 10 to the target pressure. First, the CVS 36 is activated to close and block the flow through the CVS fluid passage 60. Once the CVS 36 is closed, the pump 30 is activated to suck air from the second port 66 that is in fluid communication with the atmosphere. The air is guided through the filter 32 through the pump inlet 71 into the pump 30. The pump 30 discharges the air through the pump outlet 72 into the pump fluid passage 62, through the umbrella valve, and reaches the canister 22. The pump 30 continues to suck air into the evaporative emission system 10 until the evaporative emission system 10 reaches the target pressure, at which point the LDM 28 enters the leak diagnosis mode. During the leak diagnosis mode, the CVS 36 remains closed to block the air flow through the CVS fluid passage 60. The pump 30 is turned off, and the pressure difference between the canister 22 and the pump 30 causes the sealing disc 55 of the umbrella valve to seal the seat 57, effectively isolating the evaporative emission system 10 from the atmosphere.

[0040] In Figures 1 to 3 the example described, the leak boundary of the system 10 includes the fuel filler 14 and the cap 16, the purge valve 26, the fresh air side of the canister 22 (the side connected to the LDM 28 at the first port 64), the vapor dome chamber of the fuel tank 12, and the vapor pipelines connecting all components (including the pump fluid passage 62).

[0041] Figures 4 to 8Shows another example of the evaporative emission system 10. In this example, the FTIV system 240 is arranged within the LDM housing 46, rather than between the fuel tank 12 and the canister 22. In this configuration, the canister 22 is still positioned between the fuel tank 12 and the LDM 28. Specifically, as Figure 5 shown, the FTIV system 240 is arranged within the LDM housing 46 between the first port 64 and the CVS 36 and between the first port 64 and the pump 30. This arrangement of the FTIV system 240 allows for a more compact design of the evaporative emission system 10 and eliminates the need for the check valve 38. Additionally, the FTIV system 240 includes a solenoid valve 241 electrically controlled by the LDM controller 44 and a mechanical bypass system 242 that automatically responds to a positive or negative pressure differential between the evaporative emission system 10 and the atmosphere. As Figure 7 and Figure 8 shown, the FTIV system 240 includes a first chamber 243, a second chamber 244, and a third chamber 245. The first chamber 243 is in fluid communication with the first port 64. The first chamber 243 includes a release hole 250 that fluidly connects the first chamber 243 to the second chamber 244. The mechanical bypass system 242 facilitates fluid communication between the second chamber 244 and the third chamber 245. The solenoid valve 241 provides an alternative path for fluid flow and, when open, facilitates fluid flow directly between the first chamber 243 and the third chamber 245. In Figures 4 to 8 the example shown, the LDM 28 has six operating modes: vacuum mode, leak diagnostic mode, refueling mode, overpressure release mode, underpressure release mode, and non-operating mode.

[0042] The LDM 28 performs the vacuum mode and the leak diagnostic mode during a leak test. To initiate the leak test, the LDM 28 performs the vacuum mode, and the LDM controller 44 instructs the pump 30 to evacuate air from the evaporative emission system 10 until the evaporative emission system 10 reaches a target pressure. Additionally, the LDM controller 44 opens the solenoid valve 241 of the FTIV system 240 and closes the CVS 36 to block air flow through the CVS fluid passage 60. Thus, during the vacuum mode, air is directed through the pump fluid passage 62 and is directed to the second port 66 and vented to the atmosphere. Once the target pressure in the evaporative emission system 10 is reached, the LDM 28 performs the leak diagnostic mode. When the LDM 28 performs the leak diagnostic mode, the LDM controller 44 shuts off the pump 30, closes the solenoid valve 241 of the FTIV system 240, and opens the CVS 36.

[0043] In Figures 4 to 8In the example of the evaporative emission system 10 shown, the leak boundary of the system 10 includes the fuel filler 14 and the cap 16, the purge valve 26, the fresh air side of the canister 22 (the side connected to the LDM 28 at the first port 64 leading to the FTIV system 240), and the vapor dome chamber of the fuel tank 12.

[0044] When the LDM 28 is in the refueling mode, the pump 30 is closed. During refueling of the fuel tank 12, the pressure within the evaporative emission system 10 increases. The pressure sensors 50, 52 detect the pressure increase caused by the accumulation of fuel vapor, and if the pressure difference between the evaporative emission system 10 and the atmosphere exceeds a stored threshold, the LDM controller 44 instructs the solenoid valve 241 of the FTIV system 240 to open. Opening the solenoid valve 241 allows excess fuel vapor from the evaporative emission system 10 to be directed through the open CVS 36 and the CVS fluid passage 60, and further discharged to the atmosphere through the second port 66.

[0045] The mechanical bypass system 242 of the FTIV 240 is configured to perform both an overpressure relief mode and an underpressure relief mode. The overpressure relief mode is performed when the pressure of the fuel tank 12 reaches 28 kPa to 34 kPa. During the execution of the overpressure relief mode, the solenoid valve 241 is closed, the pump 30 is closed, while the CVS 36 is open. As Figure 8 shown, the first housing 254 is defined by a first housing member 255 and a second housing member 256. A sealing surface 257 and a release spring mechanism 258 are provided within the first housing 254. The release spring mechanism 258 is configured such that when the pressure reaches 28 kPa to 34 kPa, the release spring mechanism 258 is compressed, and the sealing surface 257 disengages from the wall 259 of the first housing member 255, thereby allowing vapor to enter the third chamber 245 of the FTIV system 240 from the second chamber 244. Then, the vapor is directed from the third chamber 245 to the CVS fluid passage 60 and through the CVS 36. Then the vapor is directed to the second port 66 and discharged to the atmosphere.

[0046] The underpressure relief mode is performed when the pressure of the fuel tank 12 is between -13 kPa and -9 kPa. During the execution of the underpressure relief mode, the solenoid valve 241 of the FTIV system 240 is closed, the pump 30 is closed, while the CVS 36 is open. Air enters the second port 66 from the atmosphere and is directed by the CVS fluid passage 60 through the CVS 36 and to the third chamber 245 of the FTIV system 240. As Figure 8As shown, the second chamber 244 further includes an air supply spring mechanism 260 disposed within the second housing 261. The second housing 261 is concentrically disposed within the first housing 254. The second housing 261 includes an orifice 263 at one end that fluidly connects the release hole 250 to the third chamber 245. As Figure 8 shown, a sealing plate 262 is fixed to the end of the air supply spring mechanism 260 and forms a seal with the second housing 261 to prevent air from flowing through the orifice 263 when flowing in the direction from the first port 64 to the second port 66. Thus, during the underpressure release mode, when air flows in the direction from the second port 66 to the first port 64, the air exerts pressure on the sealing plate 262, causing the air supply spring mechanism 260 to compress and the sealing plate 262 to disengage from the second housing 261. Then, air flows through the orifice 263 and through the void in the second housing 261 to the release hole 250. The air passes through the release hole 250 and is directed to the canister 22 through the first port 64.

[0047] The LDM 28 is also configured to perform a non - operating mode during which the solenoid valve 241 of the FTIV system 240 is closed, the CVS 36 is open, and the pump 30 is closed. In the non - operating mode, when the pressure in the fuel tank 12 is less than 28 kPa, the release spring mechanism 258 is not compressed, and when the fuel tank pressure is greater than - 9 kPa, the air supply spring mechanism 260 is not compressed.

[0048] Regarding Figures 1 to 8 each of the embodiments shown, the LDM 28 includes the hardware and software necessary to determine whether the system 10 has a leak to the atmosphere.

[0049] The LDM controller 44 is used for: A) determining whether the pressure sensor reading passes or fails and directly returning a pass or fail indication to the engine controller 40, or B) collecting pressure sensor 52 information and directly reporting this information to the engine controller 40 so that the engine controller 40 can determine whether it passes or fails. However, this pressure reading indicates pass / fail. During the leak test, the pressure sensor 52 is in fluid communication with the pump fluid passage 62 and monitors the pressure conditions generated by the pump 30 in the system 10. The pressure sensor 52 communicates with the LDM controller 44, and the LDM controller 44 determines whether there is a pressure change within a predetermined amount of time in the evaporative emission system that may indicate a leak. The pressure change detected by the pressure sensor 52 and monitored by the LDM controller 44 can indicate a leak. The OBDII system 42 communicates with and / or is integrated with the engine controller 40 and uses the pressure information from the LDM controller 44 to generate an engine fault code that can be stored, and this engine fault code is used to illuminate the "Check Engine" light on the vehicle dashboard, indicating that vehicle service is required.

[0050] The LDM controller 44 and the OBDII system 42 may be integrated or separate, but the engine controller 40 is separate from the LDM controller. In terms of the hardware architecture, such a controller may include a processor, a 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 connections. The local interface may have additional elements for implementing communication, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers. In addition, the local interface may include address, control, and / or data connections for implementing proper communication among the above components.

[0051] A controller may be a hardware device for executing software (especially software stored in the memory). The processor may be a custom or commercially available processor, a central processing unit (CPU), an auxiliary processor among several processors associated with the controller, a semiconductor-based microprocessor (in the form of a microchip or chipset), or any device commonly used for executing software instructions.

[0052] The memory may include any one 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.). In addition, the memory may include electronic, magnetic, optical, and / or other types of storage media. The memory may also have a distributed architecture, where various components are located far from each other but can be accessed by the controller.

[0053] The software in the memory may include one or more separate programs, each of which includes an ordered list of executable instructions for implementing a logical function. System components embodied as software may also be interpreted as a source program, an executable program (object code), a script, or any other entity including a set of instructions to be executed. When configured as a source program, the program is translated by a compiler, an assembler, an interpreter, etc., which may or may not be included in the memory.

[0054] When the controller is running, its processor may be configured to execute the software stored in the memory, transfer data to and from the memory, and generally control the operation of the computing device according to the software. The software in the memory is read in whole or in part by the processor, possibly buffered within the processor, and then executed.

[0055] The systems 10, LDM 28, and methods of operation described above are merely exemplary. It will be understood that the proper operation of system 10 depends highly on the desired operation of various fluid valves (here pneumatic), which must open and close reliably when commanded by the LDM controller 44 to transfer and block flow as needed during evaporative emission system test procedures and normal engine operation. Additionally, those skilled in the art will recognize that the terms "air," "vapor," and "fluid" may be used interchangeably within the scope of the present invention.

[0056] It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiments, other arrangements will benefit therefrom. Although a particular sequence of steps is shown, described, and claimed, it should be understood that the steps may be performed, separated, or combined in any order, unless otherwise stated, and still benefit from the present invention.

[0057] Although the different examples have specific components as shown in the drawings, embodiments of the present invention are not limited to those specific combinations. Some components or features from one example may be used in combination with features or components from another example. For example, the disclosed pumps may be used in applications other than vehicle evaporative systems.

[0058] Although example embodiments have been disclosed, those of ordinary skill in the art will recognize that certain modifications will fall within the scope of the claims. Accordingly, the appended claims should be studied to determine their true scope and content.

Claims

1. A leakage detection module, characterized in that: include: a housing, wherein the housing is positioned between the canister and the atmosphere, and the housing includes a first port connecting the housing fluid to the canister and a second port connecting the housing fluid to the atmosphere; a tank valve solenoid disposed within the housing and in fluid communication along a first fluid passage between the first port and the second port, the tank valve solenoid being movable between an open position and a closed position; a pump disposed within the housing and in fluid communication along a second fluid passage between the first port and the second port, wherein the first fluid passage and the second fluid passage are parallel to each other; A fuel tank isolation valve system for facilitating fluid flow between a tank and the atmosphere, wherein the fuel tank isolation valve system is arranged within the housing between the first port and the first fluid passage and between the first port and the second fluid passage, and the fuel tank isolation valve system is in fluid communication with the first port, the first fluid passage, and the second fluid passage, the fuel tank isolation valve system further comprising a first chamber, a second chamber, and a third chamber, the first chamber, the second chamber, and the third chamber together defining a plurality of fluid paths through the fuel tank isolation valve system, the fuel tank isolation valve system further comprising a solenoid valve and a mechanical bypass system, wherein the solenoid valve is electrically controlled to open and close and regulate the transfer of fluid through a first fluid path among the plurality of fluid paths, and the mechanical bypass system automatically responds to a positive or negative pressure differential across the chambers and regulates the transfer of fluid through a second fluid path among the plurality of fluid paths.

2. The leakage detection module according to claim 1, characterized in that: The first chamber is positioned between the first port and the second chamber, the second chamber is positioned between the first chamber and the third chamber, and the third chamber is positioned between the second chamber and the first fluid channel and between the second chamber and the second fluid channel.

3. The leakage detection module according to claim 1, characterized in that: The first fluid path transfers fluid between the first chamber and the third chamber.

4. The leakage detection module according to claim 1, characterized in that: The second fluid path transfers fluid from the first chamber to the second chamber to the third chamber, and also from the third chamber to the second chamber to the first chamber.

5. The leakage detection module according to claim 4, characterized in that: The release hole between the first chamber and the second chamber fluidly connects the first chamber and the second chamber.

6. The leakage detection module according to claim 5, characterized in that: A pressure relief valve is positioned between the second chamber and the third chamber to control the transfer of fluid flowing in a direction from the first port to the second port.

7. The leakage detection module according to claim 5, characterized in that: An air supply spring is positioned between the second chamber and the third chamber to control the transfer of fluid flowing in a direction from the second port to the first port.

8. An evaporative emission system, characterized in that: Comprising the leak detection module according to claim 1, the evaporative emission system further comprising: an engine configured to provide vehicle propulsion; a fuel tank configured to contain fuel and fuel vapor selectively supplied to the engine; a charcoal canister configured to store the fuel vapor from the fuel tank; A purge valve is in fluid communication with the canister and is configured to selectively provide the fuel vapor to the engine in response to a purge command.

9. A leakage detection module, characterized in that: include: a housing, wherein the housing is positioned between the canister and the atmosphere, and the housing includes a first port connecting the housing fluid to the canister and a second port connecting the housing fluid to the atmosphere; a tank valve solenoid disposed within the housing and in fluid communication along a first fluid passage between the first port and the second port, the tank valve solenoid being electronically controlled by a controller to move between an open position and a closed position; a pump disposed within the housing and in fluid communication with the first port and the second port along a second fluid passage between the first port and the second port, wherein the first fluid passage and the second fluid passage are parallel to each other; an umbrella check valve disposed within the housing and in fluid communication between the first port and the pump along the second fluid passage, wherein the umbrella check valve is a one-way mechanical valve configured to communicate fluid flow from the second port to the first port along the second fluid passage and to prevent communication of fluid from the first port to the second port along the second fluid passage; A pressure sensor is in fluid communication with at least one of the first port and the second port.

10. The leakage detection module according to claim 9, characterized in that: The umbrella check valve includes a stem secured to a male sealing disk.

11. The leakage detection module according to claim 10, characterized in that: The second fluid passage includes a seat positioned perpendicular to and across the second fluid passage, and the seat is configured to receive the umbrella check valve.

12. The leakage detection module according to claim 11, characterized in that: The seat receives the umbrella check valve such that the stem protrudes through a first side of the seat and the sealing disk is pressed flush with an opposing second side of the seat.

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