Abstract:
A central tire inflation/deflation system (CTIS) with a novel valve that may deflate more quickly and may deflate to a lower pressure than the previously known central tire inflation/deflation system valves. Also, the present valve may not be temperature sensitive, at least because the present valve does not require trapped air behind a diaphragm to operate the valve. The present valve may be placed into existing CTIS&#39;s in place of existing valves, without modifying pneumatic lines of the existing CTIS&#39;s. Thus, the present valve may be operated by a single fluid flow line, receive pressure from the single fluid flow line, and exhaust to the single fluid flow line. A second communication line, either a pneumatic pilot line or an electrical line, is not necessary, which allows the present valve to be retrofit into an existing CTIS without adding weight or complication from additional components.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/056,207 filed Sep. 26, 2014, which is incorporated herein by reference. 
       FIELD OF INVENTION 
       [0002]    The present invention relates generally to tire inflation systems, and more particularly to a fluid valve for central tire inflation/deflation systems. 
       BACKGROUND 
       [0003]    A central tire inflation/deflation system (CTIS) is a system that may provide control over the air pressure in each tire of a vehicle as a way to improve performance on different surfaces. For example, lowering the air pressure in a tire creates a larger area of contact between the tire and the ground and makes driving on softer ground much easier. It also does less damage to the surface. This is important for certain work sites, such as agricultural fields. 
         [0004]    Drivers of vehicles with a CTIS may directly control pressure in each tire to enhance mobility of the vehicle based on the terrain. Also, the CTIS may maintain a desired pressure to counteract leaks in each tire. 
         [0005]    CTIS&#39;s typically include an air supply source in selective fluid communication with a tire via a pneumatic conduit. The pneumatic conduit may include a valve with a pressure-side port for allowing the air supply source to provide pressurize the tire and alternatively for allowing the tire to deflate. Typically, the pressure-side port fluidly connects to only a single fluid flow line. The single fluid flow line carries airflow from the pressure source to the valve and carries exhaust airflow from the tire via the pressure-side port of the valve. 
         [0006]    Previous valves include a spring-loaded diaphragm to keep the valve in a closed state. In the closed state, a pressure chamber fluidly connected to the pressure-side port provides pressurized fluid from the air supply source, and a control orifice of the valve provides pressurized fluid from the tire to the diaphragm. The control orifice has significantly smaller cross-sectional area compared to pressure chamber to limit back pressure sensitivity of the diaphragm. Ideally, providing air pressure above a threshold value to the pressure-side port displaces the diaphragm to open the valve, and lowering the pressure at the pressure-side port below the pressure-side port immediately closes the valve to prevent fluid flow in or out of the associated tire. 
       SUMMARY OF INVENTION 
       [0007]    The present invention provides a central tire inflation/deflation system (CTIS) with a novel valve that may deflate more quickly and may deflate to a lower pressure than the previously known central tire inflation/deflation system valves. Also, the present valve may not be temperature sensitive, at least because the present valve does not require trapped air behind a diaphragm to operate the valve. The present valve may be placed into existing CTIS&#39;s in place of existing valves, without modifying pneumatic lines of the existing CTIS&#39;s. Thus, the present valve may be operated by a single fluid flow line, receive pressure from the single fluid flow line, and exhaust to the single fluid flow line. A second communication line, either a pneumatic pilot line or an electrical line, is not necessary, which allows the present valve to be retrofit into an existing CTIS without adding weight or complication from additional components. 
         [0008]    The present valve may include a valve member and a damper operably connected to the valve member to prevent immediate closure of the valve by dampening movement of the valve member to a closed position. Preventing immediate closure of the valve allows the valve to overcome several shortcomings of the above mentioned valve with a pressure sensitive diaphragm (“diaphragm valve”). 
         [0009]    The valve of the present application does not require a comparatively small control orifice, at least because the present valve is not sensitive to back pressure on the control side. Without a small control orifice, the fluid may flow more freely to allow the present valve to deflate or inflate more quickly than the diaphragm valve. 
         [0010]    Once opened, the valve of the present application does not require a reference pressure from a pressure source to remain open for a prescribed period of time open. The pressure source may be completely fluidly disconnected from the present valve during the prescribed period of time open. Fluidly disconnecting the pressure source from the present valve allows the associated deflating tire to quickly deflate with reference to ambient pressure. By contrast, the previous the diaphragm valve requires a reference pressure above ambient pressure from a pressure source via the single fluid flow line. The reference pressure required for the diaphragm valve hinders deflation of the associated tire and prevents deflation of the associated tire below the reference pressure—such as to ambient pressure. 
         [0011]    The present valve may include a first inlet/outlet port and a second inlet/outlet port to allow fluid to flow through the valve in either direction when open. The valve may include a reset member to shift the valve member to an open position when a reset pressure threshold is met at the first inlet/outlet port. The reset member may quickly return to an open position to transition the valve to an open state. Once the valve is in the open state, the damper may prevent immediate closure of the valve to allow the valve to remain open for a prescribed period of time, thereby allowing fluid to flow from either one of the ports to the other until the damper allows the valve member to close. 
         [0012]    According to one aspect of the invention, a valve for use in an inflation/deflation system, particularly for use in a central tire inflation/deflation system, may include a valve body having a first inlet/outlet port fluidly connectable to a second inlet/outlet port, a valve member within the valve body for fluidly disconnecting the first inlet/outlet port and the second inlet/outlet port, the valve member being moveable from a first position to a second position, and a damper operably connected to the valve member to dampen movement of the valve member from the second position to the first position. Wherein in a first state the first inlet/outlet port is fluidly disconnected from the second inlet/outlet port by the valve member, wherein the valve would transition to a second state when a fluid pressure at the first inlet/outlet port is at or above a prescribed pressure threshold, when in the second state the first inlet/outlet port would be fluidly disconnected from the second inlet/outlet port and wherein the valve would transition to a third state from the second state when the fluid pressure is below the prescribed pressure threshold while the valve is in the second state, when in the third state the first inlet/outlet port would be fluidly connected to the second inlet/outlet port while the damper will dampen movement of the valve member from the second position to the first position to maintain the valve in the third state for a prescribed period of time. 
         [0013]    The valve may further include the valve body forming a primary chamber, the primary chamber being fluidly connectable to the first inlet/outlet port and the second inlet/outlet port, the damper having a portion moveable from a first position to a second position by a first force, and moveable from the second position to the first position by a second force, wherein the first force is less than the second force, the valve member extending along a central axis, and moveable within the primary chamber, a timing resilient member biasing the valve member in a first axial direction to bias the valve member in the first position, a reset member moveable within the primary chamber to move the valve member from the first position to the second position, wherein when the valve member abuts the reset member the first inlet/outlet port and the second inlet/outlet port are fluidly disconnected, wherein in the first state, the valve member and the reset member abut one another within a first portion of the primary chamber to fluidly disconnect the first inlet/outlet port and the second inlet/outlet port, wherein in the second state, the valve member and the reset member abut one another within a second portion of the primary chamber, the second portion of the primary chamber being axially spaced in a second axial direction opposite the first axial direction from the first portion of the primary chamber, wherein in the third state, the valve member and the reset member are axially spaced from one another to allow fluid flow therebetween, thereby fluidly connecting the first inlet/outlet port and the second inlet/outlet port. A central tire inflation/deflation system may include the valve. 
         [0014]    According to another aspect of the invention, a method of operating a valve for use in an inflation system, may include providing the valve, the valve including a valve body having a first inlet/outlet port fluidly connectable to a second inlet/outlet port, a valve member within the valve body for fluidly disconnecting the first inlet/outlet port and the second inlet/outlet port, the valve member being moveable from a first position to a second position, and a damper operably connected to the valve member to dampen movement of the valve member from the second position to the first position, wherein in a first state the first inlet/outlet port is fluidly disconnected from the second inlet/outlet port by the valve member, providing fluid with a fluid pressure at or above a prescribed pressure threshold at the first inlet/outlet port, transitioning the valve to a second state based on the fluid pressure being at or above the prescribed pressure threshold, wherein in the second state the first inlet/outlet port is fluidly disconnected from the second inlet/outlet port, reducing the fluid pressure below the prescribed pressure threshold at the first inlet/outlet port, and transitioning the valve to a third state based on the fluid pressure being below the prescribed pressure threshold, dampening movement of the valve member from the second position to the first position with the damper to maintain the valve in the third state for a prescribed period of time, wherein in the third state the first inlet/outlet port is fluidly connected to the second inlet/outlet port. The method may include operating a plurality of the valves. 
         [0015]    The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a schematic view of a central tire inflation/deflation system of a vehicle including a plurality of exemplary valves in a closed state fluidly disconnecting a control system from each of a plurality of vehicle tires. 
           [0017]      FIG. 2  is a schematic view of a portion of the central tire inflation/deflation system of  FIG. 1  including the exemplary valve in a reset state fluidly disconnecting a first inlet/outlet port of the valve from a second inlet/outlet port of the valve. 
           [0018]      FIG. 3  is a schematic view of a portion of the central tire inflation/deflation system of  FIG. 1  including the exemplary valve in an open state fluidly connecting the first inlet/outlet port of the valve to the second inlet/outlet port of the valve. 
           [0019]      FIG. 4  is a top view of the valve of  FIG. 1  assembled with a wheel assembly. 
           [0020]      FIG. 5  is a side view of the valve of  FIG. 1 . 
           [0021]      FIG. 6  is a cross-section view of the valve in a closed state taken along the line  7 - 7  of  FIG. 5 . 
           [0022]      FIG. 7  is a partial view of the cross-section view of the valve of  FIG. 6 . 
           [0023]      FIG. 8  is a cross-section view of the valve taken along the line  8 - 8  of  FIG. 6  including a restrictive orifice. 
           [0024]      FIG. 9  is a partial view of the cross-section view of the valve of  FIG. 8  including a quick close port. 
           [0025]      FIG. 10  is a cross-section view of the valve in a reset state taken along the line  6 - 6  of  FIG. 5 . 
           [0026]      FIG. 11  is a cross-section view of the valve in an open state taken along the line  6 - 6  of  FIG. 5 . 
           [0027]      FIG. 12  is a cross-section view of a valve of another embodiment in a closed state. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    The principles of this present application have particular application to central tire inflation/deflation system valves for allowing inflation and deflation of vehicle tires, and thus will be described below chiefly in this context. It will be appreciated that principles of this invention may be applicable to other fluid systems where it is desirable to reduce or increase pressure of a fluid in a reservoir. For example, the novel valve of the present invention may be utilized in a fluid system other than a CTIS. 
         [0029]    Referring now in detail to the drawings, and initially to  FIG. 1 , a portion of a vehicle with a central tire inflation/deflation system  10  is illustrated schematically. The central tire inflation/deflation system  10  may include a pressure source  12 , a control system  14 , a controller  16  that may control the pressure source  12  and the control system  14 , four of valves  18 , four of fluid reservoirs, such as four vehicle tires  20 , and one or more fluid flow lines  22   a - 22   b.    
         [0030]    The controller  16  may include a computer processor and a memory device to operate the pressure source  12  and the control system  14 . Operation of the pressure source  12  and the control system  14  allows the controller  14  to control fluid flow from the pressure source  12  to operate each valve  18 . Communication lines, illustrated as dashed lines, may operably connect the controller  16  to various components of the pressure source  12  and the control system  14  to allow operation of each valve  18 . For example, the communication lines may allow electrical impulses to be communicated. In an embodiment, the communication lines are able to carry electrical signals to and from the controller. In another embodiment, the controller may bi-directionally communicate with components of the vehicle, for example to determine a speed of the vehicle. 
         [0031]    The controller  16  may operate the pressure source  12  and the control system  14  to control each valve  18  to be in a closed state, a reset state (also known as an “initialized state”), or an open state. Each valve  18  may remain in the open state for a prescribed period of time to allow each corresponding vehicle tire  20  to be inflated or deflated. 
         [0032]    The pressure source  12  may include a fluid pump  30 , such as a pneumatic compressor, a cooler  32 , an air dryer  34 , and a system reservoir  36 . The fluid pump  30  may include an intake port for receiving ambient fluid, such as ambient air, and may include an outlet fluidly connected to an inlet of the cooler  32 . The cooler  32  may include an outlet fluidly connected to an inlet of the air dryer  34 . The air dryer  34  may include an outlet fluidly connected to an inlet of the system reservoir  36 . 
         [0033]    The controller  16  may initiate the fluid pump  30  to suction ambient fluid, such as ambient air. If the ambient fluid is a compressible fluid, the fluid pump  30  may pressurize the fluid as the fluid pump  30  provides the fluid to the system reservoir  36  via the cooler  32  and the air dryer  34 . For example, if the fluid pump  30  includes a compressor, the compressor may compress ambient air to provide pressurized air to the system reservoir  36  via the cooler  32  and the air dryer  34 . 
         [0034]    The fluid pump  30  may discharge pressurized fluid out of the outlet of the fluid pump  30  to provide the pressurized fluid to the inlet of the cooler  32 . The cooler  32  may cool the pressurized fluid, which may cause the pressurized fluid to condense. For example, if the pressurized fluid is pressurized air, the pressurized air may condense which may cause the water in the pressurized air to condense. 
         [0035]    The cooler  32  may discharge cooled pressurized air from the outlet of the cooler  32  to provide the cooled pressurized air to the inlet of the air dryer  34 . The air dryer  34  may remove water molecules from the rest of the cooled pressurized air to prevent water from building up in the system reservoir  36 , the control system  14 , each valve  18 , or each vehicle tire  20 . 
         [0036]    The air dryer  34  may discharge dried pressurized air out of the outlet of the air dyer  34  to provide the dried pressurized air to the inlet of the system reservoir  36 . In an embodiment, the fluid pump may provide fluid directly to the system reservoir. 
         [0037]    The system reservoir  36  may hold pressurized fluid until the controller  16  instructs the system reservoir  36  discharge the pressurized fluid from an outlet of the system reservoir  36  to provide the pressurized fluid to an inlet of the control system  14  for operating each valve  18  and/or for inflating the corresponding vehicle tire  20 . For example, the system reservoir  36  may hold pressurized air and discharge the pressurized air to the inlet of the control system  14 . In an embodiment, the fluid pump may provide fluid directly to the control system. 
         [0038]    The system reservoir  36  may provide pressurized fluid to each vehicle tire  20  via the fluid flow line  22   a  when the control system  14  fluidly connects the system reservoir  36  to each valve  18  and the valve  18  is open. 
         [0039]    Each valve  18  may include a first inlet/outlet port  60  fluidly connected to an outlet of the control system  14 , and may include a second inlet/outlet port  62  fluidly connected to the corresponding vehicle tire  20  via a fluid flow line. In an embodiment, more than four valves are provided, for example, 6 or 8 valves may be provided. In another embodiment less than four valves are provided. 
         [0040]    In the closed state, the valve  18  may be closed, thereby fluidly disconnecting the first inlet/outlet port  60  from the second inlet/outlet port  62 . In the reset state (as shown in  FIG. 2 ), the valve  18  may be closed. In the open state (as shown in  FIG. 3 ), the valve  18  may be open, thereby fluidly connecting the first inlet/outlet port  60  to the second inlet/outlet port  62 . As illustrated schematically, the valve  18  may remain in the open state for a prescribed period of time. While open, the valve  18  may allow the vehicle tire  20  to be inflated or to be deflated. 
         [0041]    The control system  14  may include one or more fluid flow lines  22   c - 22   e , four of supply valves  64 , four of vent valves  66 , a supply pressure sensor  68 , and four of inflation/deflation pressure sensors  70 . In another embodiment, the fluid flow lines of the control system may form at least a portion of the fluid flow lines of the central tire inflation/deflation system that fluidly connect the control system to the pressure source and to each valve. In another embodiment, the fluid flow lines of the central tire inflation/deflation system—that connect the control system to the pressure source and to each valve—may form at least a portion of the fluid flow lines of the control system. 
         [0042]    Each fluid flow line  22   c - 22   e  may fluidly connect each supply valve  64  and each vent valve  66  to at least one of the pressure source  12  or to the valve  18 . Each fluid flow line  22   c  may fluidly connect the inlet of the corresponding supply valve  64  to the outlet of the pressure source  12 . For example, each fluid flow line  22   c  may fluidly connect to the fluid flow line  22   a.    
         [0043]    Each fluid flow line  22   d  may fluidly connect the outlet of the corresponding supply valve  64  to the first inlet/outlet port  60  of the corresponding valve  18 . For example, each fluid flow line  22   d  may fluidly connect to the corresponding fluid flow line  22   b . Fluidly connecting each supply valve  64  to the corresponding first inlet/outlet port  60  allows each supply valve  64  to provide pressurized fluid to the corresponding first inlet/outlet port  60  to control each valve  18 . 
         [0044]    Controlling each valve  18  to open allows the pressure source  12  to provide pressurized fluid through the fluid flow line  22   a  to the control system  14  to each fluid flow line  22   b  and to the vehicle tire  20 . The pressurized fluid may flow into each valve  18  through the corresponding first inlet/outlet port  60  and flow out of each valve  18  through the corresponding second inlet/outlet port  62  to allow the pressurized fluid to flow into each vehicle tire  20 , which may cause inflation of each vehicle tire  20 . 
         [0045]    Controlling each valve  18  to open also allows each vehicle tire  20  to provide pressurized fluid through the corresponding fluid flow line  22   b  to the control system  14  where the pressurized fluid may be expelled through the corresponding vent valve  66 . The pressurized fluid may flow into each valve  18  through the corresponding second inlet/outlet port  60 , through the corresponding first inlet/outlet port  60 , through the corresponding fluid flow line  22   b , and through the corresponding fluid flow line  22   e . From the corresponding fluid flow line  22   e , the pressurized fluid may flow to the corresponding vent valve  66  and may be exhausted by the corresponding vent valve  66 , which may cause deflation of the vehicle tire  20 . 
         [0046]    Each fluid flow line  22   e  may fluidly connect the corresponding vent valve  66  to each corresponding valve  18 . For example, each fluid flow line  22   e  may fluidly connect to the corresponding fluid flow line  22   d  to fluidly connect to the outlet of the corresponding vent valve  66 . 
         [0047]    Each supply valve  64  may be in communication with the controller  16  and fluidly connected to the first inlet/outlet port  60  of the corresponding valve  18  via the corresponding fluid flow lines  22   b ,  22   d . When the system reservoir  36  holds pressurized fluid the pressurized fluid may be provided to the first inlet/outlet port  60  when the corresponding supply valve  64  is open. Providing pressurized fluid to each first inlet/outlet port  60  allows the corresponding vehicle tire  20  to inflate when the valve  18  is in the open state. In an embodiment, more than four supply valves are provided. In another embodiment less than four supply valves are provided. 
         [0048]    Each vent valve  66  may be in communication with the controller  16  and fluidly connected with the first inlet/outlet port  60  of the corresponding valve  18  via the corresponding fluid flow lines  22   b ,  22   d ,  22   e . The controller  16  may open each vent valve  66  independently to fluidly connect the corresponding first inlet/outlet port  60  with ambient air. Connecting each first inlet/outlet port  60  with ambient air allows the corresponding vehicle tire  20  to deflate to ambient air when the corresponding valve  18  is in the open state. In an embodiment, more than four vent valves are provided. In another embodiment less than four vent valves are provided. 
         [0049]    The supply pressure sensor  68  may be operably connected to each fluid flow line  22   c , which may fluidly connect the outlet of the pressure source  12  and the inlet of each supply valve  66 . The supply pressure sensor  68  may be in communication with the controller  16  to provide the controller  16  with a reading of the pressure of the pressurized fluid provided by the pressure source  12 . 
         [0050]    Each inflation/deflation pressure sensor  70  may be operably connected to the corresponding fluid flow line  22   d , which may fluidly connect the corresponding first inlet/outlet port  60  with the corresponding supply valve  64  and the corresponding vent valve  66 . The inflation/deflation pressure sensor  70  may be in communication with the controller  16  to provide the controller  16  with a reading of the pressure of fluid flowing between each supply valve  64  and the corresponding valve  18 . In an embodiment, more than four inflation/deflation pressure sensors are provided. In another embodiment less than four inflation/deflation pressure sensors are provided. 
         [0051]    When the controller opens each supply valve  64  and closes the corresponding vent valve  66 , the pressurized fluid from the pressure source  12  may flow to the corresponding valve  18 . Each supply pressure sensor  68  and the corresponding inflation/deflation pressure sensor  70  may provide the pressure readings to the controller  16 . The pressure reading of each inflation/deflation pressure sensor  70  may rise to a level equal to the pressure reading of the corresponding supply pressure sensor  68 . For example, when each valve  18  is open and the corresponding vehicle tire  20  is inflated to 20 pounds per square inch gage (psig), the pressure reading of the corresponding pressure sensor  68  and the corresponding inflation/deflation pressure sensor  70  may be 20 psig. 
         [0052]    Alternatively, when each valve  18  is closed and the corresponding vehicle tire  20  is inflated to 15 psig, the pressure reading of the corresponding pressure sensor  68  and the corresponding may be 20 psig. If a predetermined pressure level of each vehicle tire  20  is 20 psig, the corresponding valve  18  should be opened to allow each vehicle tire  20  to be inflated to 20 psig. 
         [0053]    The controller  16  may be configured to determine whether the valve  18  should to be opened and to determine whether the vehicle tire  20  should be inflated or deflated. For example, the controller  16  may have an input for a user to select the predetermined pressure level for each vehicle tire  20 . The controller  16  may operate the pressure source  12  and the control system  14  to inflate or deflate each vehicle tire  20  to reach the selected predetermined pressure level. 
         [0054]    To facilitate inflation and deflation of the vehicle tires  20 , the controller  16  may determine the current state of the valves  18 . For example, the controller  16  may determine whether each valve  18  is in the closed state, reset state, or the closed state based on a history of pressurized fluid provided to the valve  18  at the direction of the controller  16 . The controller  16  may store the history in the memory device. 
         [0055]    The history stored may include the pressure level of pressurized fluid provided by the pressure source  12 , the pressure level of pressurized fluid provided by each supply valve  64 , and a time history of each pressure level. The history stored may also include a timeline of operation of the pressure source  12 , the supply valve  64 , and the vent valve  66 . 
         [0056]    For example, each valve  18  may be configured to have a reset pressure threshold at the corresponding first inlet/outlet port  60  that is greater than an opening pressure threshold at the first inlet/outlet port  60 . The reset pressure (also known as an “initialized pressure”) threshold may be greater than the vehicle tire  20  pressure to counter the vehicle tire  20  pressure. The reset pressure may counter any biasing force that biases the valve  18  in the closed state. 
         [0057]    Each valve  18  may be configured to transition from the closed state to the reset state in a prescribed reset time period. The prescribed reset time period may be 0.5 seconds or less when pressurized fluid is provided to the first inlet/outlet port  60 . The valve  18  may also be configured to transition from the reset state to the open state in a prescribed period of time reset. For example, the valve  18  may be configured to transition from the reset state to the open state in 0.5 seconds or less once pressure begins to lower at the first inlet/outlet port  60 . 
         [0058]    The valve  18  may be configured to transition from the open state to the closed state in a prescribed period of time open. The prescribed period of time open may be 30 seconds. In an embodiment, the prescribed period of time open is less than 30 seconds. In another embodiment, the prescribed period of time open is greater than 30 seconds. 
         [0059]    The memory device of the controller  16  may include the configurations of each valve  18  and maintain a record of each in action made by the pressure source  12  or the control system  14 . In an embodiment, the opening pressure threshold at each first inlet/outlet port may be greater than a maximum desired pressure level of fluid within the vehicle tire. The maximum desired pressure level may be a maximum manufacturer recommended pressure rating of the vehicle tire. 
         [0060]    When resetting each valve  18 , the controller  16  may keep a record of providing the pressurized fluid at or above the reset pressure threshold to the corresponding first inlet/outlet port  60  of each valve  18  for 0.5 seconds or longer. The controller  16  may determine that each valve  18  is in the reset position based on the known pressure provided to each first inlet/outlet port  60  for the prescribed period of time. 
         [0061]    When opening the valve  18 , the controller  16  may keep a record of lowering the pressure level of the pressurized fluid below the opening pressure threshold at each first inlet/outlet port  60  to allow the corresponding valve  18  to transition from the reset state to the open state. The controller  16  may adjust the fluid flow from the pressure source  12  to adjust the pressure of the pressurized fluid to a pressure below the opening pressure threshold to transition the valve  18  into the open state. The controller  16  may adjust and/or maintain the fluid flow from the pressure source  12  to maintain the pressure of the pressurized fluid at a pressure below the opening pressure threshold to prevent the valve  18  from transitioning to the reset state from the open state. 
         [0062]    The controller  16  may determine that each valve  18  is in the open state based on the known pressure at the corresponding inflation/deflation pressure sensor  70  and an amount of time lapsed since pressure level lowered below the opening pressure threshold. Once opened, each valve  18  may close after the prescribed period of time open. The controller  16  may determine whether each valve  18  has closed based on the amount of time lapsed since opening each valve  18  and the pressure values provided by the corresponding inflation/deflation pressure sensor  70  over time. 
         [0063]    The controller  16  may determine the pressure level of the fluid within the vehicle tire  20  based on the pressure values provided by the supply pressure sensor  68  and the inflation/deflation pressure sensor  70  over time in relation to the states of the pressure source  12 , the supply valve  64 , and the vent valve  66  over time. 
         [0064]    Once the pressure level within the vehicle tire  20  is determined, the controller  16  may determine whether the valve  18  should be re-opened to either inflate or deflate the vehicle tire  20  based on a comparison of the selected pressure level for the vehicle tire  20  compared to the pressure level of the vehicle tire  20  determined by the controller  16 . 
         [0065]    If the determined pressure level is below the selected pressure level, the controller  16  may open the valve  18 , the system reservoir  36 , and the supply valve  64  to inflate the vehicle tire  20 . While the valve  18  is in the open state, the controller  16  may adjust and/or maintain the fluid flow from the pressure source  12  to maintain the pressure of the pressurized fluid at a pressure below the opening pressure threshold and above the determined pressure of fluid within the vehicle tire  20  to inflate the vehicle tire  20 . 
         [0066]    If the determined pressure level is above the selected pressure level, the controller  16  may open the valve  18  and the corresponding vent valve  66  to deflate the corresponding vehicle tire  20 . While the valve  18  is in the open state, the controller  16  may adjust and/or maintain the fluid flow from the pressure source  12  to maintain the pressure of the pressurized fluid at a pressure below the opening pressure threshold and below the determined pressure of fluid within the vehicle tire  20  to deflate the vehicle tire  20 . The controller  16  may keep the valve  18  open or re-open the valve  18  until the pressure of the fluid inside the vehicle tire  20  reaches the selected pressure level. In an embodiment, the controller may keep the keep the valve open or re-open the valve until the pressure of the fluid inside the vehicle tire reaches ambient air pressure. 
         [0067]    Fluid pressure levels may vary inside one of the vehicle tires  20  and at the corresponding inflation/deflation pressure sensor  70  as the corresponding valve  18  is repeatedly re-opened to deflate air inside the vehicle tire  20 . A spike of pressure above the reset pressure threshold may occur each time the valve  18  is reset and a following drop in pressure may indicate the valve  18  is open. For example, after about 1 second a spike of pressure may reset the valve  18 . After about 0.5 seconds, the pressure may drop to allow the valve  18  to open. 
         [0068]    The air pressure within the vehicle tire  20  may drop as the air within the vehicle tire  20  vents from the vehicle tire  20 . The air pressure measured by the inflation/deflation pressure sensor  70  may gradually drop with a reference pressure of 0.0 psig as the valve  18  transitions from the opened state to the closed state. 
         [0069]    As the vehicle tire  20  deflates, the pressure of the air within the vehicle tire  20  and the pressure of the air measured by the inflation/deflation pressure sensor  70 —while the valve  18  is open—may reduce each subsequent re-opening of the valve  18   
         [0070]    The pressure measured by the inflation/deflation sensor  70  may correlate with the air pressure within the vehicle tire  20 . Thus, a pressure sensor is not needed within the vehicle tire  20  to determine pressure of the air within the vehicle tire  20 . 
         [0071]    When the vehicle tire  20  is being inflated, the inflation/deflation sensor  70  would measure the same initial spike of air pressure. After lowering the air pressure to the opening pressure threshold, the air pressure measured by the inflation/deflation sensor  70  would increase at an increasing rate as valve  18  closes, until after the prescribed period of time open when the inflation/deflation sensor  70  reaches the pressure of the pressurized air provided by the pressure source  12  ( FIG. 1 ). As the vehicle tire  20  is inflated the pressure within the vehicle tire  20  may gradually increase at a decreasing rate as the valve  18  closes. 
         [0072]    Turning to  FIG. 4 , a portion of a wheel assembly  100  may include a wheel  102 , one of the vehicle tires  20 , and the valve  18  assembled into the wheel  102 . The valve  18  may be placed at a radially outward portion of the wheel  102  that is off-set from a wheel axis (not shown) that the wheel  102  rotates about. In an embodiment, the valve  18  is placed at another location of the wheel  102 . In an embodiment, more than four vehicle tires are provided. In another embodiment less than four vehicle tires are provided. 
         [0073]      FIG. 5  is a side view of the valve  18  including a valve body  120 . The valve body  120  may define the first inlet/outlet port  60  and define a second inlet/outlet port  62  that circumscribes the central axis A. The valve body  120  may be partially formed by two separate housing bodies  120   a ,  120   b  that sealingly connect to one another to form an outer housing of the valve body  120 . The second inlet/outlet port  62  and the first inlet/outlet port  60  may be formed in the housing body  120   b  and may open toward a direction that faces the wheel  102  ( FIG. 4 ). 
         [0074]    The first inlet/outlet port  60  may circumscribe a central axis A. For example, the first inlet/outlet port  60  may be cylindrical for receiving a male connector (not shown) of a fluid flow line leading to the control system  14 . 
         [0075]    The second inlet/outlet port  62  may be radially outwardly spaced from the first inlet/outlet port  60  and may be fluidly connected to the vehicle tire  20 . The second inlet/outlet port  62  may be cylindrical for receiving a male connector (not shown) of a fluid flow line leading to the vehicle tire  20 . 
         [0076]      FIG. 6  is a cross-section view of the valve  18 . The valve  18  may include a valve member  122 , a damper  124  operably connected to the valve member  122 , a timing resilient member  126 , a reset member  128  moveable within a primary chamber  130  formed by the valve body  120 , and a reset resilient member  132  for biasing the reset member  128 . 
         [0077]    The reset member  128  may include a reset piston  134 . The reset piston  134  may have a radially outer profile perpendicular to the central axis A that is the same as a radially inner profile of an inner surface  136  of the valve body  120  to allow the reset piston  134  to move axially along the inner surface  136  within the primary chamber  130 . The reset piston  134  may be cylindrical and may have a circular radially outer profile that matches the radially inner profile of the inner surface  136 . 
         [0078]    The reset piston  134  may include a radially outwardly facing groove  140  for securing a reset sealing member  142 . The reset sealing member  142  may seal against the reset piston  134  and the inner surface  136  to prevent fluid flow between the inner surface  136  and the piston  134  when the piston  134  is stationary or moving. 
         [0079]    The reset piston  134  may include a flow passage  144  for allowing fluid to flow between the first inlet/outlet port  60  and the second inlet/outlet port  62 . The flow passage  144  may be at least partially formed by a cylindrical neck  146  of the reset piston  134 . 
         [0080]    The cylindrical neck  146  may extend axially away from the valve member  122 . The cylindrical neck  146  may include a radial passage  148  for allowing fluid flow therethrough. The radial passage  148  may be axially offset from an axial end of the cylindrical neck  146  that may engage an inner surface  150  of the valve body  120 . 
         [0081]    The flow passage  144  may extend away from a seat  152  of the reset piston  134 . The seat  152  may receive an axial end of the valve member  122  to fluidly disconnect the first inlet/outlet port  60  from the second inlet/outlet port  62 . 
         [0082]    The reset piston  134  may be axially moveable within the primary chamber  130  to move from an open position to a reset position. The reset piston  134  is illustrated in the open position in  FIG. 6  ( FIG. 10  illustrates the reset position). The reset piston  134  may be axially disposed in a first portion of the primary chamber  130  when the reset piston  134  is in the open position. The valve  18  may be closed when the reset piston  134  is in the open position within the first portion of the primary chamber  130  while the valve member  122  is in a closed position abutting the reset piston  134  within the primary chamber  130 . 
         [0083]    The reset piston  134  may be moveable to the reset position and back to the open position. The reset resilient member  132  may bias the reset member  128  toward the open position. Biasing the reset member  128  allows the reset piston  134  to quickly return to the open position from the reset position when the pressurized fluid provided to the first inlet/outlet port  60  is at or below the opening pressure threshold. 
         [0084]    The reset resilient member  132  may bias the reset piston  134  in a first axial direction extending from the second portion of the primary chamber  130  to the first portion of the primary chamber  130 . The reset resilient member  132  may be any type of resilient member. For example, the reset resilient member  132  may be a spring, such as a metal spring. 
         [0085]    The reset resilient member  132  may extend from an axially intermediate portion  154  of the valve body  120  to an axially facing surface of the reset piston  134 . The axially facing surface may face in a second axial direction opposite the first axial direction. 
         [0086]    The reset resilient member  132  may also circumscribe at least a portion of the timing resilient member  126 . For example, the resilient member  128  may be entirely radially outward of the valve member  122  to prevent the resilient member  128  from interfering with movement of the valve member  122 . 
         [0087]    The reset piston  134  may be axially disposed in a second portion of the primary chamber  130  when the reset piston  134  is in the reset position. The second portion of the primary chamber  130  may be formed at an axially opposite end of the primary chamber  130  as the first portion of the primary chamber. When the valve member  122  is in a closed position, the reset piston  134  may move the valve member  122  to an open position in the second portion of the primary chamber  130  when the reset piston  134  moves from the open position to the reset position. For example, when the valve  18  is closed the reset piston  134  may be in the open position and the valve member  122  may be in the closed position. Providing pressurized fluid at or above the reset pressure threshold may cause the reset piston  134  to move from the open position to the reset position. While moving, the reset piston  134  may move the valve member  122  to the open position to place the valve  18  in the reset state. 
         [0088]    The valve member  122  may be within the valve body  120  for fluidly disconnecting the first inlet/outlet port  60  and the second inlet/outlet port  62 . The valve member  122  is illustrated in the closed position in  FIG. 6  ( FIGS. 10 and 11  illustrate the open position of the valve member  122 ) and may be moveable from the closed position to the open position. The damper  124  may dampen movement of the valve member  122  from the open position to the closed position. Dampening movement of the valve member  122  from the open position to the closed position allows the valve  18  to remain in the open state for the prescribed period of time open. 
         [0089]    The damper  124  may include a timing chamber  156 , a timing piston  158  moveable within the timing chamber  156 , a check valve  160  for creating a pressure differential within the timing chamber  156 , and a restrictive orifice  162  (shown in  FIGS. 8 and 9 ) for delaying pressure equalization within the timing chamber  156 . The timing chamber  156  may be formed by an inner surface  164  of the intermediate portion  154  that circumscribes the central axis A and an axially facing surface of the valve body  18 . The timing chamber  156  may be filled with a fluid, such as air. 
         [0090]    The timing piston  158  may be moveable by a reset force from an initial position at a first portion of the timing chamber  156  to a reset position (as shown in  FIGS. 10 and 11 ) at a second portion of the timing chamber  156 . The timing piston  158  may have a radially outer profile perpendicular to the central axis A that is the same as a radially inner profile of the inner surface  164  of the intermediate portion  154  to allow the timing piston  158  to move axially along the inner surface  164  within the timing chamber  156 . The timing piston  158  may be cylindrical and may have a circular radially outer profile that matches the radially inner profile of the inner surface  164 . 
         [0091]    The axially intermediate portion  154  may be axially fixed to the housing bodies  120   a ,  120   b  to form an end of the primary chamber  130  axially opposite the first inlet/outlet port  60 . For example, the axially intermediate portion  154  may have outer threads to threadingly attach to inner threads of the housing bodies  120   a ,  120   b.    
         [0092]    The valve  18  may include seals  165 ,  167 ,  169 ,  171 . Each seal  165 ,  167 ,  169 ,  171  may be any suitable seal, such as an o-ring. The seal  165  may be radially disposed between the intermediate body  154  and the housing body  120   a  to prevent fluid flow between the intermediate portion  154  and the housing body  120   a.    
         [0093]    The seal  167  may be axially disposed between the radially outer surfaces of the housing bodies  120   a ,  120   b  to prevent fluid flow therebetween. 
         [0094]    The seal  169  may be disposed in an axially facing groove of the housing body  120   b  circumscribing the central axis A radially between the first inlet/outlet port  60  and the second inlet/outlet port  62 . When assembled into the vehicle wheel  102 , the seal  169  may seal against the housing body  120   b  and the vehicle wheel  102  to prevent fluid from flowing outside of the housing body  120   b  between the first inlet/outlet port  60  and the second inlet/outlet port  62 . 
         [0095]    The seal  171  may be disposed in an axially facing groove of the housing body  120   b  circumscribing the central axis A radially outward of the second inlet/outlet port  62 . When assembled into the vehicle wheel  102  ( FIG. 4 ), the seal  171  may seal against the housing body  120   b  and the vehicle wheel  102  to prevent fluid flowing radially outward from the second inlet/outlet port  62 . 
         [0096]    As best shown in  FIG. 7 , the check valve  160  may be disposed within the timing piston  158  to prevent fluid flow from the first portion of the timing chamber  156  to the second portion of the timing chamber, and to allow fluid flow from the second portion of the timing chamber  156  to the first portion of the timing chamber  156 . 
         [0097]    The check valve  160  may include a sealing member  166  and one or more fluid passages  168 . The sealing member  166  may be disposed in a radially outward facing groove of the timing piston for abutting the inner surface  164  of the axially intermediate portion  154 . Fluid flow through each fluid passage  168  may be prevented when the sealing member  166  is engaged with the inner surface  164  and the timing piston  158 . For example, the sealing member  166  may be any suitable seal, such as an o-ring seal, and the o-ring seal may engage with the inner surface  164 . The o-ring seal may also engage with an axial facing surface  170  of the timing piston  158  when the timing piston  158  moves from the reset position to the initial position. 
         [0098]    Each fluid passage  168  may extend axially from an axially facing surface  172  of the timing piston  158  toward the sealing member  166 . For example, each fluid passage  168  may extend to a radially outward facing surface  174  of the timing piston  158  to allow the sealing member  166  to recede radially inwardly into each fluid passage  168 . In an embodiment, the fluid passage may extend axially through the timing piston and the sealing member may seal the fluid passage when the timing piston moves in the first axial direction. 
         [0099]    The timing piston  158  may be moveable from the reset position toward the initial position with a closing force that allows the valve member  122  to close. The closing force may be greater than the reset force. For example, the closing force may be based on the fluid resistance against the timing piston  158  as the timing piston  158  moves from the reset position to the initial position. The fluid resistance may be much greater when moving the timing piston  158  from the reset position to the initial position compared to the reverse, because fluid pressure may slowly equalize throughout the timing chamber  156  as the timing piston  158  moves. 
         [0100]    The reset force may be based on fluid resistance against the timing piston  158  as the timing piston  158  moves from the initial position to the reset position. The fluid resistance may be negligible when moving the timing piston  158  to the reset position compared to the reverse. The fluid pressure may equalize throughout the timing chamber  156  more quickly as the timing piston  158  moves to the reset position compared to moving to the initial position. 
         [0101]    Turning to  FIG. 8 , the timing resilient member  126  may bias the valve member  122 , the timing piston  158 , and the reset piston  134  in the first axial direction to bias the valve  18  in the closed state. The timing resilient member  126  may be any type of resilient member. For example, the timing resilient member  126  may be a spring, such as a metal spring. 
         [0102]    The timing resilient member  126  may be at least partially disposed within the valve member  122 . For example, the timing resilient member  126  may extend axially from a radially inwardly extending axially facing ledge  176  of the valve member  122  to an axially facing surface  178  of the valve body  120 . The radially inwardly extending axially facing ledge  176  may face in the second axial direction opposite the axially facing surface  178 . 
         [0103]    The timing resilient member  126  may also circumscribe the central axis A at least partially within the timing piston  158  and/or the valve member  122 . For example, the timing resilient member  126  may be entirely radially inward of the axially intermediate portion  154 , of the reset resilient member  132 , and of the timing piston  158 . 
         [0104]    The timing resilient member  126  may move the timing piston  158  from the reset position to the initial position. When moving the timing piston  158  from the reset position to the initial position fluid may be forced through the restrictive orifice  162  until the timing piston  158  approaches the first portion of the timing chamber  156 . 
         [0105]    The restrictive orifice  162  may restrict fluid flow from the first portion of the timing chamber  156  to the second portion of the timing chamber  156  to delay pressure equalization between the first portion and the second portion. 
         [0106]    The restrictive orifice  162  may be disposed within the timing piston  158  or may form a portion of the timing piston  158 . For example, the restrictive orifice  162  may be a foraminous portion of the timing piston  158 . The foraminous portion may be formed by laser drilling one or more microscopic axial through passages for restricting fluid flow through the timing piston  158 . In an embodiment, the restrictive orifice is an axially extending flow passage or a plurality of axially extending flow passages that restrict fluid flow. 
         [0107]    The valve body  120  may include a radially outwardly extending passage  179  and one or more axially extending fluid passages  181  that may fluidly connect the second inlet/outlet port  62  to the radially outwardly extending passage  179 . The radially outwardly extending passage  179  may be axially spaced from the first portion of the primary chamber  130  to allow fluid flow through the radially outwardly extending passage  179  when the reset piston  134  is in the open position. Axially spacing the radially outwardly extending passage  179  allows the reset piston  134  to prevent fluid flow through the radially outwardly extending passage  179  when the reset piston is in the reset position. 
         [0108]    The radially outwardly extending passage  179  may have a cross-sectional area that have a fluid volume flow rate capacity that is equal to or greater than a fluid volume flow rate capacity of the axially extending fluid passage  181 . 
         [0109]    The valve  18  may include a quick close port  180  to reduce a fluid pressure differential between the first portion and the second portion of the timing chamber  158  as the timing piston  158  reaches an end of its stroke while moving from the reset position to the initial position. The quick close port  180  may fluidly connect the first portion to the second portion of the timing chamber  158 . For example, the quick close port  180  may allow fluid to flow in the second axial direction from the first portion of the timing chamber to the second portion of the timing chamber. 
         [0110]    As best shown in  FIG. 9 , the quick close port  180  may include a radially outwardly recessed portion  182  of the axially intermediate portion  154 , a radially inwardly recessed portion  184  of the axially intermediate portion  154 , and a sealing member  186 . The radially outwardly recessed portion  182  may extend in the second axial direction from an axial end  188  of the first portion of the timing chamber  158 . 
         [0111]    The radially outwardly recessed portion  182  may extend in the second axial direction from the axial end  188  to allow fluid to flow through the radially outwardly recessed portion  182  past the timing piston  158  as the timing piston  158  is anywhere from 5% to 20% away from the end of its stroke in the first axial direction. For example, the axial length of the radially outwardly recessed portion  182  may be configured to allow fluid to flow through the radially outwardly recessed portion  182  past the timing piston  158  when the timing piston  158  has reached an axial position that would indicate 10% of time remaining for the timing piston  158  to reach the end of its stroke without the quick close port  180 . 
         [0112]    The radially inwardly recessed portion  184  may be recessed in the first axial direction and define at least a portion of the timing chamber. The sealing member  186  may be disposed at the axial end  188  between the radially outwardly recessed portion  182  and the radially inwardly recessed portion  184  to fluidly seal the timing chamber  156 . Fluidly sealing the timing chamber  156  fluidly disconnects the quick close port  180  from the primary chamber  130  from the second inlet/outlet port  62  (shown in  FIG. 8 ) to allow fluid to flow through the primary chamber  130  without affecting operation of the timing piston  158  and the quick close port  180 . 
         [0113]    When the timing piston  158  moves from the reset position to the initial position, a radially outward portion of the sealing member  166  disengages from the inner surface  164  at the radially outwardly recessed portion  182  to allow fluid to flow through the radially outwardly recessed portion  182 . Allowing fluid flow quickens pressure equalization between the first portion and the second portion of the timing chamber  156  to reduce resistance to movement of the timing piston in the first axial direction. 
         [0114]    Turning to  FIG. 10 , the valve  18  is illustrated in the reset state where the reset piston  134  has moved into the reset position to move the valve member  122  into the open position. Providing fluid with a fluid pressure at or above the reset pressure threshold at the first inlet/outlet port  60  may transition the valve member  122  and the reset piston  134  into the open position and the reset position, respectively. 
         [0115]    The valve member  122  may include a poppet  190  and an end seal  192  at an axial end of the poppet  190  for sealing against the reset piston  134 . In an embodiment, the valve member is another type of valve, for example a sliding valve. 
         [0116]    The poppet  190  may extend axially along the central axis A through a central through hole in the intermediate portion  154 . Extending through the intermediate portion  154  allows the poppet  190  to engage the reset piston  134  in the primary chamber  130  and to engage the timing piston  158  in the timing chamber  156 . 
         [0117]    The poppet  190  may be axially fixed to the timing piston  158 . For example, the timing piston  158  and a body  194  of the poppet  190  may be formed in one-piece to allow the poppet  190  to be moveable with the timing piston  158 . 
         [0118]    The body  194  may define a moveable chamber  196  for housing a portion of the timing resilient member  126 . The body  194  may also form the radially inwardly extending axially facing ledge  176  for abutting the timing resilient member  126 . For example, the body  194  and the radially inwardly extending axially facing ledge  176  may circumscribe the central axis A. 
         [0119]    The body  194  may include a flow passage  198  that is fluidly connected to a variable volume chamber  200  (shown best in  FIG. 8 ) through the moveable chamber  196 . The flow passage  198  may extend from an axial end of the poppet  190  that is engageable with the reset piston  134  to the moveable chamber  196 . 
         [0120]    The variable volume chamber  200  and the moveable chamber  196  may be fluidly disconnected from the timing chamber  156  by a seal  202  that engages with the body  194  and the valve body  120 . For example, the seal  202  may be axially spaced from the timing piston  158  in the second axial direction to engage a radially outward facing surface of the body  194  at a location between the timing piston  158  and variable volume chamber  200 . 
         [0121]    The variable volume chamber  200  may have a minimum volume when the poppet  190  is in the open position. The variable volume chamber  200  may have a maximum volume that is larger than the minimum volume when the poppet  190  is in the closed position (shown in  FIG. 8 ). The volume of the variable chamber  200  may reduce as the poppet  190  moves from the closed position to the open position. 
         [0122]    Fluid contained within the variable chamber  200  and the moveable chamber  196  may flow through the flow passage  198 . Fluid flowing through the flow passage  198  may flow to the primary chamber  130  to prevent fluid pressure build-up that may resist opening of the poppet  190 . 
         [0123]    The end seal  192  may be an axially facing seal, such as an o-ring, that is engageable with the reset piston  134  to seal against the reset piston  134 . When engaged, the seal  192  and/or a radially outward extending flange of the poppet  190  may abut an axial face of the reset piston  134  to prevent fluid flow therebetween. Preventing fluid flow between the reset piston  134  and the seal  192  may fluidly disconnect the first inlet/outlet port  60  and the second inlet/outlet port  62 . For example, the fluid flow from the first inlet/outlet port  60  through the primary chamber  130  to either second inlet/outlet port  62  may be prevented. 
         [0124]    Turning to  FIG. 11 , the valve  18  is illustrated in the open state. When the valve  18  is in the reset state, reducing the fluid pressure at or below the opening pressure threshold at the first inlet/outlet port  60  may transition the valve  18  to the open state. 
         [0125]    When the valve  18  is in the open state, the seal  192  may be axially spaced from the reset piston  134  to allow fluid to flow between the poppet  190  and the reset piston  134 . The poppet  190  may be in the open position and the reset piston  134  may be in the open position to allow fluid to flow from the first inlet/outlet port  60  to each second inlet/outlet port  62 . 
         [0126]    The timing piston  158  may dampen movement of the poppet  190  from the open position to the closed position. For example, the timing resilient member  126  may bias the poppet  190  to close while the fluid in the first portion of the timing chamber  156  increases in pressure relative to the fluid in the second portion of the timing chamber  156 . The fluid in the first portion may force the check valve  160  to prevent fluid flow. 
         [0127]    The increased pressure of the fluid in the first portion may cause the sealing member  166  to seal against the inner surface  164  to prevent fluid flow therebetween. Fluid from the first portion of the timing chamber  156  may only be able to equalize pressure with the fluid in the second portion of the timing chamber  156  by flowing through the restrictive orifice  162  (shown in  FIG. 8 ) until the timing piston  158  reaches the quick close port  180  (shown in  FIG. 8 ). Restricting the fluid flow may delay closure of the poppet  190  to allow fluid to flow through the primary chamber  130  between the first inlet/outlet port  60  and each second inlet/outlet port  62 . 
         [0128]    The delayed closure may allow the poppet  190  to remain axially spaced from the reset piston  134  for the prescribed period of time open. The prescribed period of time open may be anywhere from 10-60 seconds preferably 20-40 seconds, and more preferably 30 seconds. In an embodiment, the prescribed period of time open may be based on a size of the vehicle tire, a desired pressure of the vehicle tire, and desired deflation rates of the vehicle tire. 
         [0129]    Pressure at the second inlet/outlet port  62  may be reduced below the opening pressure threshold. For example, the pressure provided to the first inlet/outlet port  60  may lowered, or completely removed, and the poppet  190  may remain axially spaced apart from the reset piston  134  for the prescribed period of time open. While the popper  190  is axially spaced from the reset piston  134 , fluid may flow from the second inlet/outlet port  62  to the first inlet/outlet port  60 . 
         [0130]    The fluid pressure at the second inlet/outlet port  62  may reduce toward ambient pressure by expelling fluid from the second inlet/outlet port  62  to the first inlet/outlet port  60 . For example, the first inlet/outlet port  60  may be fluidly connected to ambient air, such as when the corresponding vent valve  66  ( FIG. 1 ) is open. 
         [0131]    The poppet  190  may remain axially spaced from the reset piston  134  during the prescribed period of time open when the pressure at the first inlet/outlet port  60  is equal to ambient pressure. The fluid pressure at the second inlet/outlet port  62  may be reduced to ambient pressure when the first inlet/outlet port  60  is at ambient pressure and the valve  18  is opened. For example, ambient pressure may be 0.0 psig and the poppet  190  may remain axially spaced from the reset piston  158  for the prescribed period of time open. 
         [0132]    Turning now to  FIG. 12 , an exemplary embodiment of the valve is shown at  218 . The valve  218  is substantially the same as the above-referenced valve  18 . In addition, the foregoing description of the valve  18  is equally applicable to the valve  218  except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the valves may be substituted for one another or used in conjunction with one another where applicable. 
         [0133]    The valve  218  may include a damper  124  that is operably coupled to a valve member  122  to dampen movement of a valve member  122  from an open position to a closed position. 
         [0134]    The damper  124  may include a piezoelectric element  220 , a resistor  222 , and a capacitor  224 . 
         [0135]    The piezoelectric element  220  may be operatively connected to an end of the poppet  190 . When the poppet  190  moves from the closed position to the open position the poppet  190  may deform the piezoelectric element to generate an electric charge. For example, the piezoelectric element  220  may have a convex portion that is engaged with the end of the poppet  190 . A radially extending support member  226  may axially fix the piezoelectric element  220  to a valve body  120 . When the poppet  190  opens the convex portion may compress to generate the electric charge for the capacitor  226 . 
         [0136]    The capacitor may be operatively connected to the piezoelectric element  220  to receive electric current generated by the piezoelectric element  220  and to send electric current back to the piezoelectric element  220 . For example, a negative terminal of the capacitor  224  may be electrically connected to a negative terminal of the piezoelectric element  220  and a positive terminal of the capacitor  224  may be electrically connected to a positive terminal of the piezoelectric element  220 . The negative terminal of the capacitor  224  may be electrically connected to the negative terminal of the piezoelectric element  220  via the resistor  222 . 
         [0137]    The resistor  222  may be connected in series with the capacitor  224  and the piezoelectric element  220 . For example, the resistor  222  may reduce electrical current flowing to or from the piezoelectric element  220 . 
         [0138]    When the piezoelectric element  220  is deformed to generate the charge, the current may flow through the resistor  222  to the capacitor  224  to charge the capacitor  226 . 
         [0139]    When the capacitor  224  discharges to the piezoelectric element  220 , the resulting electrical current may flow through the resistor  222 . 
         [0140]    The resistor  222  may have a resistance to reduce the electrical current discharged from the capacitor  224  to delay the piezoelectric element  220  from resuming its original form, thereby dampening closure of the poppet  190 , which may close the valve  218 . For example, the resistor  222  may have a resistance based on a desired prescribed period of time open. Increasing the resistance of the resistor  222  may increase the prescribed period of time open. Decreasing the resistance of the resistor  222  may decrease the prescribed period of time open. 
         [0141]    Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.