Abstract:
A valve has a movable valve element extending across a passageway within a housing and a central aperture, either through the valve element itself or in an adjacent part of the housing, which is opened by movement of the valve element to allow fluid flow between an inlet and an outlet.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to British Patent Application No. 0917376.6, filed Oct. 5, 2009, which is incorporated herein by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a valve, in particular to a fluid valve. The valve may be used in the engine of a motor vehicle, in particular for supplying oil to the torque converter of an automatic transmission system. 
       BACKGROUND 
       [0003]    In use of a motor vehicle transmission system, oil is circulated around the components thereof. When a vehicle engine is stopped and subsequently restarted, a problem arises in that during the stop, oil has drained under the effects of gravity from the passageways of the oil circulation system. Thus, when the engine is restarted, there is a delay before the transmission system is fully operational while the empty passageways are refilled with oil. 
         [0004]    At least one aspect of the present invention seeks to provide a valve in which the above problem is overcome or reduced, at least for a period of time. In addition, other aspects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
       SUMMARY 
       [0005]    According to an embodiment of the present invention, there is provided a valve comprising a housing having an inlet, at least one outlet, and a passageway extending between the inlet and the outlet and having walls, and a moveable valve element extending inwardly from the walls across the passageway, the valve having a first portion defining an aperture which is surrounded by the passageway and a second portion for closing the aperture, wherein the valve element is movable between a first disposition, in which said aperture is closed by said second portion to substantially prevent fluid flow, and a second disposition in which said aperture is spaced from said second portion to allow fluid flow. 
         [0006]    At least one advantage of this arrangement is that, when closed, the valve is capable of preventing fluid drain back, i.e. unwanted flow of fluid in the reverse direction during periods when there is no forward flow. 
         [0007]    In one embodiment said first portion is constituted by a substantially central region of the movable valve element and said second portion is a fixed part of the housing. 
         [0008]    This enables the provision of an effective two-way check valve. 
         [0009]    In a second embodiment said first portion is constituted by the outlet and said second portion is constituted by a substantially central region of the movable valve element. This enables the provision of an effective three-way check valve. 
         [0010]    A method of operating a valve is also provided that comprises a housing having an inlet, at least one outlet, and a passageway extending between the inlet and the outlet and having walls, and a moveable valve element extending inwardly from the walls across the passageway, the valve having a first portion defining an aperture which is surrounded by the passageway and a second portion for closing the aperture, the method comprising raising a pressure applied to said inlet from a zero or low value to a relatively higher value whereby to move the valve element from a first disposition, in which said aperture is closed by said second portion to substantially prevent fluid flow, to a second disposition in which said aperture is spaced from said second portion to allow fluid flow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
           [0012]      FIG. 1  shows a sectional view of a valve in accordance with a first embodiment of the present invention in a closed configuration; 
           [0013]      FIG. 2  shows the valve of  FIG. 1  in an open configuration; 
           [0014]      FIG. 3  shows a sectional view of a valve in accordance with a second embodiment of the present invention in a closed configuration; 
           [0015]      FIG. 4  shows the valve of  FIG. 2  in an open configuration; and 
           [0016]      FIG. 5  is a top sectional view of the valve of  FIG. 3  along line F-F. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
         [0018]    When reference is made to the walls or edges of a component, this includes a reference to a single wall or edge if the component is circular. The expressions “upper” and “lower” are used to indicate relative position rather than to be limited to any particular orientation in space. 
         [0019]    Referring to the drawings,  FIG. 1  shows a side sectional view of a two-way check valve  10  in accordance with a first embodiment. The valve comprises a housing  1  having a lower part  11   b , through which passes an inlet channel  12  from a pressurized source of oil, and an upper part  11   a , through which passes an outlet channel  14  to the components of a motor vehicle transmission system.  FIG. 1  shows the situation in which no pressure is being applied via inlet  12 . 
         [0020]    Between the inlet and outlet there is defined a chamber or passageway comprising an upper part  16  and a lower part  18 . Part  16  is substantially circular in plan view and is in fluid communication with outlet channel  14 . A solid circular-cylindrical stub portion  20  of housing  11  projects into lower passageway part  18  to form an annular chamber in fluid communication with inlet channel  12 . Stub portion  20  has a planar top surface  22 . 
         [0021]    The upper and lower parts  16  and  18  of the passageway are separated by a movable valve element  30  formed by a membrane. The membrane is an integral part of a rubber seal  32  between the two housing parts  11   a ,  11   b . Thus the circular edge  34  of the membrane valve element is held fixed in position. The rubber material used is REINZ model AFM31. 
         [0022]    The membrane  30  has an outer circumferential portion  36  which, in the closed configuration of the valve shown in  FIG. 1 , bridges the orifice at the top of annular part  18  to close it off from upper part  16 . Located radially inwardly from portion  36 , the membrane has a substantially central portion  38  having a through aperture  40 . In the closed configuration of  FIG. 1 , aperture  40  abuts against the top surface  22  of stub portion  20 . 
         [0023]    The surface  22  of portion  20  is slightly higher than the bottom surface of seal  32  by a distance ‘a’. Accordingly membrane  30  is biased by surface  22  to a position slightly higher than one which it would otherwise occupy naturally. Since membrane  30  is of resilient material, it exerts a downward force on surface  22  so as to provide a seal between the top of lower passageway part  18  and aperture  40 . This serves to substantially prevent any oil leaking from inlet channel  12  to outlet channel  14  when the valve us in the closed configuration of  FIG. 1 . 
         [0024]    When pressurized oil is supplied to inlet channel  12 , the resilient membrane  30  deflects upwardly as shown in  FIG. 2  so that aperture  40  is located well clear of surface  22 . In this open configuration of the valve  10 , oil can flow freely from inlet channel  12  through lower passageway part  18 , aperture  40 , upper passageway part  16  and outlet channel  14 . When the source of pressure is disconnected from inlet channel  12 , the membrane  30  reverts to the disposition of  FIG. 1  and flow back of oil is substantially prevented. 
         [0025]    An advantage of the above-described arrangement is that the valve automatically closes when no pressure is applied. In the closed configuration, the membrane prevents the oil from leaking from the inlet to the outlet. In addition it also prevents air from entering the inlet via the outlet. Accordingly the inlet channel is always filled with oil, which in turn has the advantage of increasing the speed of response when an oil flow is needed. For example, when used in the oil feed to a torque converter in an automatic transmission, the torque converter remains filled with oil even after several hours of non-use; this has the advantage of allowing a quick start. 
         [0026]    A further advantage of the above-described arrangement is that, by suitable adjustment or calibration of the dimensions of the membrane and the various apertures and orifices, the opening of the valve can be triggered to occur at a desired pressure or flow rate. 
         [0027]    The aperture  40  is relatively large, so that oil can flow substantially unimpeded through the valve. Because the membrane is part of a seal, there is no path for the leakage of oil at the walls of the passageway. As shown, the diameter of aperture  40  is substantially equal to half of the diameter of the stub portion  20 . This leaves enough of central portion  38  to provide effective sealing. 
         [0028]    Referring now to  FIG. 3  to  FIG. 5 , there is shown a three-way check valve  110  in accordance with a second embodiment of the present invention. Integers in common with the embodiment of  FIG. 1  and  FIG. 2  are identified by the same reference numerals. The second embodiment has a different arrangement of the lower housing part  11   c  and the membrane/valve element  130 . In addition to inlet  12  and outlet  14 , the valve  110  has an additional or secondary outlet  150  which passes though lower housing part  11   c  and opens into the passageway through a hollow, circular-cylindrical channel portion  120 . Portion  120  is located substantially centrally of the lower annular part  18  of the passageway. 
         [0029]    Resilient membrane  130  is part of a flexible seal  32  between housing parts  11   a ,  11   c . It has a circumferential portion  136  which bridges the orifice at the top of annular part  18  and has four though holes  160  (see also  FIG. 5 ), which provide permanent fluid communication between passageway parts  18  and  16 . 
         [0030]    Membrane  130  further comprises a solid portion  138  located radially inwardly from portion  136 . In the partially-closed configuration of the valve shown in  FIG. 3 , portion  138  substantially closes the orifice at the top of secondary outlet  150 . Accordingly oil can flow from inlet  12  only to outlet  14 . The resilience and configuration of membrane  130 , and in particular portion  138 , serve to substantially prevent any oil leaking from inlet channel  12  to outlet channel  150 . 
         [0031]    When the pressure or flow rate prevailing at inlet channel  12  rises above a predetermined threshold value, holes  160  are no longer capable alone of passing the oil flow and membrane  130  is displaced into the configuration shown in  FIG. 4 , in which the valve  110  is open to both outlets. Substantially central portion  138  has been moved clear of the end of outlet  150  so that oil can freely flow from inlet  12  to outlet  150 . Apertures  160  are located so that they continue to permit flow from inlet  12  into upper passageway part  16  and thence to outlet  14 . When the pressure level at inlet  12  falls below a second threshold value, lower than the first-mentioned threshold value, the membrane  130  reverts to the disposition of  FIG. 3 , and flow into outlet  150  is substantially prevented. 
         [0032]    The arrangement in accordance with the second embodiment has the same advantages as the first embodiment. 
         [0033]    Instead of four holes  160 , the valve  110  may have any number of holes arranged in any desired pattern. 
         [0034]    In a modification of the second embodiment, the valve has two separate membranes, a lower membrane corresponding to membrane  130 , and an upper membrane corresponding to membrane  30  and overlying the lower membrane. The lower membrane is more resistant to pressure than the upper membrane; in other words the upper membrane is more resilient. Such an arrangement acts as a two-stage valve. With no or low pressure, the valve is completely closed. Upon the pressure exceeding a first threshold, the upper membrane lifts and flow is permitted from inlet  12  to outlet  14 . Upon the pressure being raised beyond a second threshold, the lower membrane also lifts and flow is permitted from inlet  12  to both outlets  14  and  150 . It has to be ensured that the upper membrane does not block the apertures in the lower membrane when both membranes are lifted. 
         [0035]    The membrane moves between its two dispositions in a continuous manner, its final position depending on the flow. Alternatively, it may jump from one disposition to the other when a particular threshold is reached. The membrane can be made of any suitable material with sealing and elastic capabilities. It can be made of a plastic material combined with a separate spring. Alternatively, it can comprise paper or rubber adhered to a thin metal sheet. 
         [0036]    Instead of being inherently resilient, the membrane may be biased into its closed position by a separate spring member. 
         [0037]    Instead of being a membrane with fixed edges, the movable valve element may take a number of different forms. For example, it may be constructed by a resiliently-biased disc which slides within the passageway or chamber. Alternatively, the movable valve element may be a resiliently-biased pivotal flap. In these modifications, the housing portions  20 ,  120  do not need to be centrally located, but can be located at a side of the passageway. 
         [0038]    While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.