Abstract:
A tank pressure control valve which provides for both controlled and passive vacuum relief functions with an additional component in a tank purge valve. The tank pressure control valve includes a second valve in addition to a purge valve to create a small sealing area on one side that opens easily against the tank pressure with the normal magnetic forces in a purge valve. The second valve is a sealing disk, which has an aperture to allow for the flow of purge vapor. One side of the disk has sealing on a larger area so the small vacuum forces open the valve against the spring force biasing the valve to a closed position. The design of the second valve uses a disk to provide precise flow control and passive vacuum relief.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/861,576 filed Aug. 2, 2013. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates generally to a valve assembly which performs the functions of removing purge vapor from a fuel tank under pressure, and allowing passive vacuum relief of the fuel tank as necessary. 
       BACKGROUND OF THE INVENTION 
       [0003]    The amount of air pressure in a fuel tank varies with changes in temperature, and changes in the amount of fuel in the tank, such as during refueling and fuel consumption. In hot climates, the level of air pressure and amount of purge vapor in the tank is controlled by opening and closing a valve for very short pulses. This contains the vapors in the tank as much as possible, without exceeding a limit pressure for the tank. However, there are conditions where the tank also needs passive (not controlled) relief of vacuum pressure. Vacuum pressure in the fuel tank may occur during periods of fuel consumption during vehicle operation, and needs to be relieved to avoid reaching an undesirable level. However, typical valve assemblies are designed to only provide flow control, and have a separate valve used to provide vacuum relief. 
         [0004]    Accordingly, there exists a need for a valve assembly which is able to provide flow control during a purge process, and vacuum relief. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides for both controlled flow of purge vapor and passive vacuum relief functions with an additional component in a tank purge valve. The invention adds a sealing disk to a purge valve to create a small sealing area on one side that opens easily against the tank pressure with the normal magnetic forces in a purge valve. The sealing disk has an aperture in the middle to allow for the flow of purge vapor. The second side of the disk has sealing on a larger area so the small vacuum forces open the valve against the spring force which biases the valve to a closed position. The design of the present invention uses a disk to provide precise flow control and vacuum relief. 
         [0006]    In one embodiment, the invention is a tank pressure control valve assembly, which includes an overmold assembly having a first port, where the first port is in fluid communication with a fuel tank. A cap is connected to the overmold assembly, and a cap aperture is formed as part of the cap, such that the cap aperture forms part of a second port, and the cap aperture provides fluid communication between the overmold assembly cavity and the second port. The second port is in fluid communication with a carbon canister. An overmold assembly cavity having an inside surface is formed as part of the overmold assembly, and the first port is in fluid communication with the overmold assembly cavity. A solenoid assembly is disposed inside the overmold assembly adjacent the overmold assembly cavity, and the solenoid assembly controls the movement of an armature. A stopper portion is connected to the armature, and the valve assembly also includes a secondary valve member, where the stopper portion is selectively in contact with the secondary valve member. 
         [0007]    During a first mode of operation, the solenoid assembly is used to move the armature and stopper portion away from the secondary valve member, and control the flow of purge vapor flowing from the fuel tank into the first port, through the overmold assembly cavity, and out of the second port. During a second mode of operation, the overmold assembly cavity is exposed to vacuum pressure in the fuel tank, and the vacuum pressure moves the secondary valve member, the stopper portion, and the armature away from the inside surface, allowing air to pass from the second port, through the cap aperture and into the overmold assembly cavity, through the first port, and into the fuel tank, relieving vacuum pressure in the fuel tank. 
         [0008]    The secondary valve member has several components. In one embodiment, the secondary valve member includes a core portion selectively in contact with the stopper portion and the inside surface. The core portion includes a base, and a flow aperture is integrally formed as part of the base. A flange member is also integrally formed as part of the base, and is part of the core portion. An outer seal member substantially surrounds the flange member, and a lip is formed as part of the outer seal member, such that the lip is selectively in contact with the inside surface. During the first mode of operation, the stopper portion is selectively moved away from the core portion to control the amount of purge vapor flow through the flow aperture. During the second mode of operation, the vacuum pressure in the overmold assembly cavity moves the secondary valve member, the stopper portion, and the armature such that the lip moves away from the inside surface. 
         [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a diagram of part of an air flow system for a vehicle, having a tank pressure control valve assembly, according to embodiments of the present invention; 
           [0012]      FIG. 2  is a sectional view of a tank pressure control valve assembly, according to embodiments of the present invention; and 
           [0013]      FIG. 3  is an enlarged view of the circled portion of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0015]    A tank pressure control (TPC) valve having a multi-function valve assembly is shown in  FIGS. 1-3  generally at  10 . The TPC valve  10  includes an inlet port  12  in fluid communication with a fuel tank  86 . The TPC valve  10  includes a housing, which in this embodiment is an overmold assembly  14 , and disposed within the overmold assembly  14  is an actuator in the form of a solenoid assembly, shown generally at  16 , and the solenoid assembly  16  is disposed within a cavity, shown generally at  18 , formed as part of the overmold assembly  14 . The cavity  18  includes an inner wall portion  20 , and also forming part of the cavity  18  is an outer wall portion  22  of the overmold assembly  14 . 
         [0016]    The solenoid assembly  16  includes a stator insert  24  which surrounds a support  26  formed as part of the overmold assembly  14 . A first washer  28  is disposed between an upper wall  30  of the overmold assembly  14  and a bobbin  32 . The bobbin  32  is surrounded by a coil  34 , and two straps (not shown) surround the coil  34 . There is a sleeve  36  which is surrounded by the bobbin  32 , and the sleeve  36  partially surrounds a moveable armature  38 . The armature  38  includes a cavity, shown generally at  40 , and located in the cavity  40  is a spring  42 , which is in contact with an inner surface  48  of the cavity  40 . The spring  42  is also mounted on a narrow diameter portion  44  of the support  26 , and the spring  42  biases the armature  38  away from the stator insert  24 . Disposed between part of the armature  38  and the bobbin  32  is a second washer  46 . Connected to the overmold assembly  14  is a cap  50 , and formed as part of the cap  50  is a cap aperture  54  and a second port  68 . The cap aperture  54  is partially formed as part of the second port  68 , and the second port  68  is connected to and in fluid communication with a carbon canister  88 . Purge vapor is able to flow from an overmold assembly cavity, shown generally at  56 , formed as part of the overmold assembly  14 , through the cap aperture  54 , and out of the second port  68 . 
         [0017]    The armature  38  includes a first valve member, which in this embodiment is a stopper portion  58  made of a rubber or other flexible material. The stopper portion  58  includes a contact surface  60  which contacts a second or secondary valve member, shown generally at  70 , when the armature  38  is in the closed position. The stopper portion  58  includes a plurality of post members  62 , which are of the same durometer, but are of different sizes, and therefore have different levels of stiffness. The largest post members  62  are in contact with the bottom surface of the washer  46  when the armature  38  is in the closed position, as shown in  FIG. 2 . The smaller post members  62  contact the bottom surface of the washer  46  when the armature  38  moves to the open position. The spring  42  biases the armature  38  and the stopper portion  58  away from the stator insert  24  and toward the second valve member  70 , and therefore biases the armature  38  and stopper portion  58  towards the closed position. The coil  34  is energized to move the armature  38  away from the second valve member  70 , placing the solenoid assembly  16  in an open position. The more the coil  34  is energized, the further the armature  38  moves away from the second valve member  70 , and the greater number of post members  62  contact the bottom surface of the washer  46 . The movement of the armature  38  to open and close the solenoid assembly  16  controls the amount of purge vapor allowed to pass through the TPC valve  10 , and into the canister  88 . 
         [0018]    Because the post members  62  are made of rubber, the post members  62  are able to deform as the armature  38  is moved further away from the second valve member  70 . The largest post members  62  in contact with the bottom surface of the washer  46  deform first when the armature  38  moves away from the second valve member  70 . As the armature  38  moves further away from the second valve member  70 , more of the post members  62  contact the bottom surface of the washer  46 , and then begin to deform as the armature  38  moves even further away from the second valve member  70 . The deformation of the post members  62  (when the armature  38  is moved to the open position away from the second valve member  70 ) functions to dampen the movement of the armature  38 , eliminating noise, and preventing metal-to-metal contact between the armature  38  and the stator insert  24 . 
         [0019]    Disposed between the bottom surface of the washer  46  and an inside surface  64  of the cap  50  is a filter  66 . The filter  66  is made of several blades of plastic which are adjacent to one another. The filter  66  is designed to limit the size of debris and particles passing through the blades of plastic to less than 0.7 millimeters. The distance between the armature  38  and the stator insert  24  is about 1.0 millimeters, and is the maximum allowable distance between the contact surface  60  of the stopper portion  58  and the second valve member  70 . The filter  66  ensures that no particles may pass through the filter  66  that are too large to affect the functionality of the solenoid assembly  16  (the particles being too large to fit between the second valve member  70  and the stopper portion  58 ) when the armature  38  is in the open position. 
         [0020]    The second valve member  70  is disposed between the stopper portion  58  and an area  72  of the inside surface  64  surrounded by the filter  66 . The second valve member  70  includes a flow aperture  74  formed as part of a core portion  76 , where the contact surface  60  is in contact with the core portion  76  when the armature  38  is in the closed position. The core portion  76  includes a base  78  and a flange member  80 , and surrounding part of the base  78  and the flange member  80  is a outer seal member  82 . The seal member  82  includes a lip  84  selectively in contact with the area  72  of the inside surface  64  surrounded by the filter  66 . 
         [0021]    As mentioned above, the more the coil  34  is energized, the further the armature  38  and the stopper portion  58  move away from the second valve member  70 , placing the solenoid assembly  16  in an open position, allowing purge vapor to pass from the overmold assembly cavity  56 , through the flow aperture  74 , the cap aperture  54  and out of the second port  68 . The purge vapor is then able to flow into the carbon canister  88 . 
         [0022]    The valve  10  provides a flow path between the fuel tank  86  and the carbon canister  88 , where the flow path includes the inlet port  12 , the overmold assembly cavity  56 , the stopper portion  58 , the cap aperture  54 , and the second port  68 , and during process when purge vapor is removed from the fuel tank  86 , the flow aperture  74  is part of the flow path as well. The purge vapor flows through the flow path in one direction, and air for vacuum pressure relief flows in another direction. Both the stopper portion  58  and the secondary valve member  70  are disposed in this same flow path. 
         [0023]    During operation, if there is a need to allow purge vapor to move from the fuel tank  86  to the carbon canister  88 , such as during times of refueling or an increase in pressure in the fuel tank  86  due to an increase in temperature, the coil  34  is energized enough to overcome the biasing force of the spring  42  to move the armature  38  and the stopper portion  58  away from the second valve member  70 , allowing vapor in the fuel tank  86  to flow in a first direction and flow from the inlet port  12 , through the overmold assembly cavity  56 , through the flow aperture  74  of the second valve member  70 , through the flow aperture  74 , and out of the second port  68 , and into the carbon canister  88 . 
         [0024]    If the vehicle is operating under conditions such that there is a vacuum condition in the fuel tank  86 , such as during typical driving when the level of fuel in the tank  86  is reduced as the fuel is consumed, or because of a decrease in temperature when the vehicle is parked, air is allowed to pass from the canister  88  through the valve  10  and into the fuel tank  86  to relieve the vacuum pressure in the fuel tank  86 . More specifically, once the vacuum pressure in the fuel tank  86  reaches a predetermined level, air is drawn from the canister  88  through the valve  10 . The vacuum pressure applies force to the second valve member  70  such that once enough force is applied to the second valve member  70  to overcome the biasing force of the spring  42 , the armature  38 , the stopper portion  58 , and second valve member  70  move away from the inside surface  64 , such that the lip  84  is no longer in contact with the inside surface  64 , allowing air from the canister  88  to flow from the canister  88  into the second port  68 , the cap aperture  54  and into the overmold assembly cavity  56 ; the air then flows through the first port  12  into the fuel tank  86 . The air is drawn past the second valve member  70 , and more specifically the lip  84 , because the lip  84  is moved away from the inside surface  64 . The flow of air from the canister  88  to the fuel tank  86  provides a vacuum pressure relief function, preventing the vacuum pressure in the fuel tank  86  from reaching undesirable levels. 
         [0025]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.