Abstract:
An isolation valve includes a flow restrictor in a passage and having an orifice and configured to provide a first, second, and third flow paths. A spring may bias the flow restrictor to an open position that opens the second flow path. A solenoid assembly may include a coil and an armature moveable between an extended position that moves the flow restrictor to close the first, second, and third flow paths, and a retracted position that opens the first flow path. The first flow path may include a path from a first reservoir through the orifice to a second reservoir. The second flow path may include a first flow direction from the first reservoir to the second reservoir via a second path, the second path including a space between the flow restrictor and the passage. The third flow path may include a second flow direction from the second reservoir to the first reservoir via the second path.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 14/611,637 filed on Feb. 2, 2015, now U.S. Pat. No. 9,500,291, which is a continuation-in-part of U.S. patent application Ser. No. 13/011,511 filed on Jan. 21, 2011, now U.S. Pat. No. 8,944,100, which is a continuation-in-part of U.S. patent application Ser. No. 12/749,924 filed on Mar. 30, 2010, now U.S. Pat. No. 8,584,704, which are all incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present teachings relates to a valve assembly for controlling fluid flow to and from a high-pressure fuel tank, and more particularly to such a valve assembly that can be depressurized quickly. 
       BACKGROUND 
       [0003]    High-pressure fuel tanks may use an isolation valve to open and close a vapor path between the fuel tank and a purge canister. In a typical evaporative emissions system, vented vapors from the fuel system are sent to a purge canister containing activated charcoal, which adsorbs fuel vapors. During certain engine operational modes, with the help of specifically designed control valves (e.g., vapor vent valves), the fuel vapors are adsorbed within the canister. Subsequently, during other engine operational modes, and with the help of additional control valves, fresh air is drawn through the canister, pulling the fuel vapor into the engine where it is burned. 
         [0004]    For high-pressure fuel tank systems, an isolation valve may be used to isolate fuel tank emissions and prevent them from overloading the canister and vapor lines. The isolation valve itself may be a normally closed valve that is opened to allow vapor flow for tank depressurization or any other event where vapor release is desired. The vapor flow rate may be controlled to, for example, prevent corking of vent valves elsewhere in the emissions system. 
         [0005]    There is a desire for an isolation valve that can be used in high-pressure fuel tanks and that can depressurize quickly in a controlled manner to allow user access to the fuel tank within a reasonable amount of time. 
       BRIEF SUMMARY 
       [0006]    An isolation valve according to one example of the present teachings may include a flow restrictor disposed in a passage having non-parallel sides, the flow restrictor having an orifice. A flow restrictor spring may apply a biasing force on the flow restrictor to bias the flow restrictor to an open position. A solenoid assembly may include having a coil and an armature that may be moveable between (i) an extended position that overcomes the biasing force of the restrictor spring to move the flow restrictor to a closed position and to close the second orifice, and (ii) a retracted position to open the orifice. If the coil is energized, the armature may move to the retracted position to allow vapor to flow through the orifice at least until the biasing force of the flow restrictor spring overcomes a vapor pressure. The open position of the flow restrictor may allow vapor to flow through a space between the flow restrictor and the passage. 
         [0007]    An isolation valve according to another example of the present teachings may include a body including a passage having non-parallel sides and a flow restrictor disposed in the passage. The flow restrictor may include an orifice, an open position in which the flow restrictor allows vapor flow in a space between the flow restrictor and the passage, and/or a closed position in which the flow restrictor prevents vapor flow between the flow restrictor and the passage. The isolation valve may include an armature that may be movable between (i) an extended position in which the armature prevents vapor flow through the orifice, and (ii) a retracted position, in which the armature allows vapor flow through the orifice. 
         [0008]    A method of operating an isolation valve according to another example of the present teaching may include providing an isolation valve body including a passage having non-parallel sides; providing an flow restrictor in the passage. The flow restrictor may include an orifice and a piston that may be movable between (i) an open position in which the flow restrictor allows vapor flow in a space between the flow restrictor and the passage, and (ii) a closed position in which the flow restrictor prevents vapor flow between the flow restrictor and the passage. The method may include providing an armature that may be movable between (i) an extended position in which the armature prevents vapor flow through the orifice, and (ii) a retracted position, in which the armature allows vapor flow through the orifice. The method may include moving the armature to the retracted position to allow vapor to flow through the orifice, reducing a vapor pressure via vapor flowing through the orifice, and/or moving the piston gradually from the closed position toward the open position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a cross-sectional view of a valve assembly configured for controlling fuel vapor flow between a fuel tank and a purge canister, with the valve shown in a completely closed state, according to one example of the present teachings. 
           [0010]      FIG. 1A  is a magnified cross-sectional view of a depressurizing valve according one example of the present teachings. 
           [0011]      FIG. 2  is a cross-sectional view of the valve assembly shown in  FIG. 1  when a solenoid in the valve assembly is energized during a start of a depressurization process conducted before refueling of the fuel tank. 
           [0012]      FIG. 3  is a cross-sectional view of the valve assembly shown in  FIG. 1  when the solenoid is energized and the depressurizing valve is in an open position while the flow restrictor is in a closed position. 
           [0013]      FIG. 4  is a cross-sectional view of the valve assembly shown in  FIG. 1  where both the depressurizing valve and the flow restrictor are both in an open position. 
           [0014]      FIG. 5  is a cross-sectional view of a valve assembly according to another example of the present teachings. 
           [0015]      FIG. 5A  is a cross-sectional view of a valve assembly according to another example of the present teachings. 
           [0016]      FIG. 5B  is a cross-sectional view of a valve assembly according to another example of the present teachings. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to the drawings,  FIG. 1  generally illustrates a fuel system, schematically represented by numeral  10 . The system  10  may include a fuel tank  12  and a controller  14  that may regulate the operation of an engine (not shown) and its fuel delivery system (not shown). Fuel tank  12  may be operatively connected to an evaporative emissions control system that includes a purge canister  18  that may collect fuel vapor from the fuel tank  12  and subsequently release the fuel vapor to the engine. In addition, controller  14  may regulate the operation of a valve assembly  20  to selectively open and close the valve assembly  20 , which may provide over-pressure relief and/or vacuum relief for the fuel tank  12 . Valve assembly  20  may be connected to tank  12  via tank connector  24  and/to canister  18  via canister connector  26 . 
         [0018]    The valve assembly  20  itself may control fuel vapor flow between the fuel tank  12  and the purge canister  18 . Although the valve assembly  20  shown in the figures is located between the fuel tank  12  and the purge canister  18 , nothing precludes the valve assembly  20  from being located elsewhere, such as between the purge canister  18  and the engine. 
         [0019]    The valve assembly  20  may include a housing  22  that retains internal components of the valve assembly  20  in a compact manner. The valve assembly  20  may include a relief valve  28 . The relief valve  28  may include a piston  30 , which may be formed from a suitable chemically-resistant material such as an appropriate plastic or aluminum. The relief valve  28  may also include a compliant seal  32 , which may be formed from a suitable chemically-resistant elastomeric material. During operation, the seal  32  may make initial contact with the housing  22  along the seal&#39;s outer edge. After the initial contact with housing  22 , the outer edge of seal  32  may deflect to conform to the housing and seal a passage  34 . 
         [0020]    The piston  30  and the seal  32  may be combined into a unitary piston assembly via an appropriate manufacturing process, such as overmolding, as understood by those skilled in the art. The piston  30  and the seal  32  may be biased to close the passage  34 . A spring  36  or other resilient member may bias the piston and the seal  32 . The relief valve  28  may generally be used to open a vapor path between the fuel tank  12  and the purge canister  18  to relieve an extreme or over-pressure condition in the fuel tank  12 . Additional details of the operation of the relief valve  28  in conjunction with the rest of the valve assembly  20  are described in commonly-assigned, U.S. Pat. No. 8,584,704 on Mar. 30, 2010, the disclosure of which is incorporated by reference herein in its entirety. 
         [0021]    The description below will now focus on operation of the valve assembly  20 , and particularly a solenoid assembly  40  and components that operate in conjunction with it, during a depressurization operation prior to refueling. 
         [0022]    The solenoid assembly  40  includes an armature  42 , a solenoid spring  44 , and a coil  46 . The energization and de-energization of the coil  46  may be controlled by a signal from the controller  14 . The solenoid spring  44  may generate a force sufficient to urge the armature  42  out of the solenoid assembly  40  when the coil  46  is not energized. When the coil  46  is energized, the resulting magnetic forces overcome the biasing force of the solenoid spring  44  and pull the armature  42  into the solenoid assembly  40 , exposing a small orifice  49  in a flow restrictor  50  to allow vapor flow through the orifice  49  (see, e.g.,  FIG. 2 ). 
         [0023]    In one example of the present teachings, the flow restrictor  50  may be arranged inside the housing  22  and may include a piston portion  52 , which may be formed from a suitable chemically-resistant material such as an appropriate plastic or aluminum. The flow restrictor  50  may also include a compliant seal  55 , which may be formed from a suitable chemically-resistant rubber. During valve operation, the seal  55  may initially contact the housing  22  along the seal&#39;s outer edge. After initial contact with the housing  22 , the outer edge of seal  55  may deflect to conform to the housing  22  and hermetically close a passage  56  leading to the canister connector  26 . 
         [0024]    In one aspect of the present teachings, the size of the small orifice  49  in the flow restrictor  50  is selected to allow only a selected amount of flow at a maximum specified tank pressure because the size of the passage  56  is may be large enough to prevent “corking.” More particularly, without the small orifice  49  slowing vapor flow through the passage  56 , the force from rushing fuel vapors may force other valves in the system  10 , such as a fuel limit vent valve (not shown) in the fuel tank  12 , to “cork” into a closed position. Thus, the reduced size of the small orifice  49  in the flow restrictor  50  may control the vapor flow to a level that prevents corking. Vapor control may be desired for other purposes as well without 
         [0025]    Referring again to  FIG. 2 , when a user wishes to refuel the tank, the user may wish to depressurize the fuel tank first so that the potentially high pressure in the tank  12  is lowered to a specified acceptable level. However, the size of the small orifice  49  may restrict the vapor flow rate to a level that is not high enough to depressurize the tank in a reasonable amount of time. On the other hand, allowing unrestricted vapor flow through the isolation valve  10  may cause other valves in the system to cork, such as explained above. 
         [0026]    To provide closer control over vapor flow, the flow restrictor  50  may include a depressurization valve  50   a , as shown in  FIG. 1A , to allow faster tank depressurization. The depressurization valve  50   a  may be a poppet valve, wherein the small orifice  49  is in the poppet valve rather than the piston  52 . The depressurization valve  50   a  may have its own associated seal  57  that seats against the piston  52 . In examples of the present teachings, the depressurization valve  50   a  may disposed in an intermediate orifice  50   b  in the piston  52 . In one aspect of the present teachings, the size of the intermediate orifice  50   b  may be selected to allow increased vapor flow while still limiting the flow enough to prevent corking of fuel venting valves. The depressurization valve  50   a  may be biased toward an open position by a depressurization spring  50   c  supported by the piston  52 . In one aspect of the present teachings, the spring  50   c  may have a biasing force that is greater than the spring  54  biasing the flow restrictor  50  itself. 
         [0027]    The flow restrictor  50  may have two effective orifice sizes that may be opened when the solenoid assembly  40  is energized: (1) a small orifice  49  in the depressurization valve  50   a  that may ensure vapor flow rate between the tank and the canister is less than a maximum flow rate to prevent corking of fuel tank venting valves during normal valve operation; and, (2) an intermediate orifice  50   b  in the piston  52  that, in combination with the small orifice  49 , may allow faster tank depressurization, such as before a refueling operation. Also, a difference in biasing forces between the springs  54 ,  50   c  may allow the depressurization valve  50   a  to open at a given vapor pressure while the flow restrictor  50  remains in a closed position, which may allow vapor to flow simultaneously through the small orifice  49  and the intermediate orifice  50   b.    
         [0028]    In examples of the present teachings, a user may depressurize the tank  12  by, for example, pushing a button on the interior of the vehicle to send a control signal from the controller  14 . The signal may energize the coil  46 , which may create a magnetic force that withdraws the armature  42  to open the small orifice  49  and creates a flow path through the flow restrictor  50  and the passage  56 . High tank pressure may create a high vapor flow rate, which provide enough initial force to compress both springs  54 ,  50   c , keeping the piston  52  and the depressurization valve  50   a  pushed downward against the large passage  56  and restricting flow to only through the small orifice  49 . 
         [0029]    Referring to  FIG. 3 , if the spring force of the depressurization spring  50   c  biasing the depressurization valve  50   a  to an open position is larger than the spring force of the restrictor spring  54  biasing the flow restrictor  50  to an open position, and since the vapor pressure may drop soon after a small amount of vapor escapes through the small orifice  49 , the depressurization spring  50   c  may force the depressurization valve  50   a  to an open position. The open position of the depressurization valve  50 A may allow for increased vapor flow by creating two flow paths out of the tank  12 , which may include one through the small orifice  49  and one through the intermediate orifice  50   b  (e.g., in the space between the depressurization valve  50   a  and the piston  52 ). The intermediate orifice  50   b , which may be larger than small orifice  49 , may allow an increased flow rate out of the tank, which may allow the tank  12  to depressurize to a desired level quicker than through the small orifice  49  alone. 
         [0030]    Referring to  FIG. 4 , the vapor pressure may drop low enough so that the restrictor spring  54  overcomes the vapor pressure from the tank and pushes the flow restrictor  50  open as well, which may open a flow path through the large passage  56 . As shown in  FIG. 4 , the large passage  56  may be exposed when the armature  42  is withdrawn into the solenoid assembly  40  in response to a tank depressurization signal, such as noted above. This combination of lower tank pressure and withdrawn armature  42  may allow the restrictor spring  54  to extend, which may push the flow restrictor  50  upward against the armature  42  to close the small orifice  49  and intermediate orifice  50   b  and open the large passage  56 . At this point, the tank pressure may be low enough to keep the vapor flow at a lower level during the final stages of the tank depressurization process, which may prevent corking in the fuel vent valves. 
         [0031]    The varying opening sizes  49 ,  50   b ,  56 , used both alone and in combination, and the different biasing forces of the springs  44 ,  50   c  may provide fast, yet controlled, tank depressurization while still keeping the vapor flow rate low enough to prevent corking of fuel vent valves in the emissions system. 
         [0032]      FIG. 5  shows a further example of the present teachings that may increase the vapor flow rate through the valve assembly  20 . This particular example may omit a separate depressurization valve and additional orifice sizes. Instead, this example may provide for modification of the configuration of the passage  56 , the characteristics of the restrictor spring  54 , and/or the weight of components of flow restrictor  50  (e.g., piston  52 ) to permit vapor flow to increase gradually through the passage  56 . 
         [0033]    For instance, the passage  56  may include sides that may not be parallel. Passage  56  may comprise generally cylindrically shaped sides that may include arcuate sections. In an example of the present teachings, passage  56  may be funnel-shaped, which may include some or all arcuate sections of passage  56  being tapered. When the coil  46  is initially energized to initiate tank depressurization, the armature  42  may withdraw into the solenoid assembly  40 , allowing vapor to initially flow through the small orifice  49 . As the vapor pressure drops, the biasing force of the restrictor spring  54  may lift the piston  52  from the passage  56  to allow some of the vapor to bypass the flow restrictor  50  directly into the passage  56 . However, the funnel shape of the passage  56  restricts the amount of vapor flowing through the passage  56 , thereby preventing corking of the fuel vent valves. As a difference in pressure is reduced, the restrictor spring  54  may gradually force the flow restrictor  50  up the funnel-shaped passage  56  to a wider point, which may allow even more vapor to flow under and/or around the flow restrictor  50  into the passage. 
         [0034]    In previous examples of the present teachings, flow restrictor  50  may generally operate in a binary fashion, such that flow restrictor  50  is either opened or closed at a predetermined pressure. In this example of the present teachings, a funnel-shaped passage  56  may permit gradual opening and/or gradual closing of flow restrictor  50 , which may allow for reduced depressurization time without causing other vent valves to cork. Additionally or alternatively, a funnel-shaped passage  56  may allow for orifice  49  to be smaller and a smaller orifice  49  may be opened via a lower amount of force, which may allow for using a smaller solenoid assembly  40 . 
         [0035]    In a further example of the present teachings, such as generally illustrated in  FIG. 5A , passage  56  may include a sloped section  56   a , but may include non-sloped sections (e.g., may not be entirely funnel-shaped). A passage  56  with a sloped portion  56   a  may function in a similar manner as a funnel-shaped passage. For example, and without limitation, sloped portion  56   a  may gradually increase the width and/or circumference of passage  56 , which may allow for gradual opening and closing of flow restrictor  50 , and/or faster depressurization. 
         [0036]    In a further example of the present teachings, such as generally illustrated in  FIG. 5B , passage  56  may include a stepped portion  56   b . Stepped portion may include one or more steps (e.g., two, three, four, or more steps) that may gradually increase the width and/or circumference of passage  56 . 
         [0037]    In examples of the present teachings, such as generally illustrated in  FIGS. 5A and 5B , piston  52  of flow restrictor  50  may include an elongated, hollow body with a generally cylindrical shape that may include a flow path between orifice  49  and passage  56 . Seal  55  may be disposed generally between housing  22  and piston  52  and/or may define a minimum diameter of the small orifice  49 . The flow restrictor spring  54  may be disposed around the outside of piston  52  and may engage a flange  52   a  of piston  52 . The flange  52   a  may extend radially outward from the body of piston  52  and/or may extend around all or part of the circumference of piston  52 . The flow restrictor spring  54  may also engage a recess  22   a  of body  22  that may be disposed, for example, about half between the top and bottom of piston  52  when piston  52  is in the closed position. 
         [0038]    In the closed position, armature  42  may be biased by solenoid spring  44  to contact piston  52  and/or seal  55  to keep small orifice  49  closed. If solenoid assembly  40  is sufficiently energized or activated, such as in response to a signal from controller  14 , armature  42  may be lifted off of seal  55  to expose small orifice  49 . Small orifice  49  may start allowing a balancing of pressure and/or depressurization, and spring  54  may start moving piston  52  toward an open position at a predetermined pressure difference. Spring  54  may be a helical spring. As depressurization continues, piston  52  may move in passage  56  such that the gap between piston  52  and passage  56  increases via the sloped portion  56   a  and/or the stepped portion  56   b . As the gap increases, a greater vapor flow rate may be permitted, which may allow for faster depressurization. 
         [0039]    In other words, the shape of the passage  56  itself, in combination with the piston  52  diameter, may naturally create a passage  56  with a variable size to control vapor flow. Thus, the combination of the funnel-shaped, sloped, and/or stepped passage  56  and the selected biasing force of the restrictor spring  54  against the piston  52  may gradually adjust the amount of vapor released from the fuel tank  12  while adjusting the vapor flow rate via the position of the flow restrictor  50  in the passage  56  to prevent corking of fuel vent valves in the emissions system. 
         [0040]    In an example of the present teachings, the weight of one or more components of flow restrictor  50 , such as piston  52 , may be configured such that one or more of the solenoid spring  44  and the flow restrictor spring  54  may be omitted (e.g., portions of valve assembly  20  may be controlled via gravity). 
         [0041]    The foregoing descriptions of specific examples of the present teachings have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the teachings to the precise forms disclosed, and various modifications and variations are possible in light of the above teaching. It is believed that various alterations and modifications of the exemplary aspects of the present teachings may become apparent to those skilled in the art from a reading and understanding of the specification. It is intended that all such alterations and modifications are included in the present disclosure, insofar as they come within the scope of the present teachings as defined by the claims appended hereto and their equivalents.