Abstract:
The pinch valve includes a valve member movable to compress or pinch a resilient tubular element extending through a passage of a housing or body of the valve to varying extents to regulate or prevent fluid flow through the tubular element. The valve member includes a valve head configured to pinch the tubular element through a range of progressively more flow restrictive crescent shapes into a generally U-shape, and while doing so cooperates with side surfaces of the body or housing to bend or fold over lateral end portions of the tubular element that form distal ends of the U-shape. The valve member additionally includes pinch shoulders that follow the pinch head and secondarily pinch or compress the folded over end portions together to complete closure of the tubular element as the U-shape is pinched closed, to prevent leaking, trapping of fluids, and damaging the tubular element under high fluid pressures.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 62/303,161, filed Mar. 3, 2016. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates generally to a pinch valve including a valve member movable to compress or pinch a resilient tubular element extending through a passage of a housing or body of the valve to regulate or prevent fluid flow through the tubular element, and more particularly, that pinches the tubular element through a range of generally crescent shapes into a generally U-shape, and in doing so brings together and bends or folds over opposite lateral end portions of the tubular element that form the distal ends of the U-shape, respectively, then pinches them closed as the U-shape portion is pinched closed, to complete closure and prevent leaking, trapping of fluids, and damaging the tubular element under high fluid pressures. 
       BACKGROUND ART 
       [0003]    U.S. Provisional Application No. 62/303,161, filed Mar. 3, 2016, is incorporated herein by reference in its entirety. 
         [0004]    Pinch valves are well known for use in fluid flow applications requiring sanitary conditions for the fluids, such as, but not limited to, food and pharmaceutical manufacture, delivery, and distribution. Pinch valves generally include a length of a tubular element of a flexible material that carries the fluid, a length of the tubular element being disposed in a rigid valve housing, and a valve or pinch member that is pressed against the tubular element to close it completely or restrict flow through it. The tubular element can extend beyond the valve housing, or can connect to a fluid line via suitable couplers. Reference in this regard: Osborne, U.S. Pat. No. 5,730,323 entitled Automatic Pressure Regulated Liquid Dispensing Device that discloses a pinch valve generally; and Teson et al., U.S. Pat. No. 2,987,292, entitled Mechanically Operated Collapsible Valve that utilizes three balls for collapsing a tubular element in a Y shape. Reference also Dorsey et al., U.S. Pat. No. 5,938,078 entitled Valve for Beverage Dispenser that discloses an elongate pinch valve that pinches the tubular element longitudinally in a gradual manner when closing; and Phallen et al., European Patent Application Serial No. EP1099661 A1 entitled A High Speed Beverage Dispensing Method and Apparatus that utilizes an elongate pinch element for flow control through a tubular element. 
         [0005]    While the referenced and other pinch valves presumably perform adequately for their intended purposes, it has been observed that valves having a pinch member or element that pinches the tubular element only over a short distance in the flow direction have several shortcomings. One is that the pinching force must be greater or concentrated to prevent leakage thereabout. The tubular element is also subject to earlier failure due to the higher pinching force required. In the known valves that pinch the tubular element longitudinally, it is either not completely pinched closed, e.g., European Patent Application Serial No. EP1099661 A1, used for flow control only; or it is pinched flat in conformance to a flat supporting surface, e.g., U.S. Pat. No. 5,938,078, which may be prone to leakage at higher pressures, e.g., greater than a few pounds per square inch. 
         [0006]    It has also been observed that when the tubular element is pinched closed in some known valves, particularly those utilizing thicker walled tubular elements, small passages can be remain at the ends of the pinched together portions, essentially, where portions of the tubular element are folded over, through which leakage can occur. 
         [0007]    As another observed shortcoming of several known pinch valves wherein one or both ends of the tubular element attaches to a coupling via frictional fit, e.g., using one or more barbs, it has been found that the closing action of the valve or pinch member can stretch or deform the tubular element past its elastic limit so as to form a small cavity between the tubular element and the coupling that can collect and trap fluid in which contaminants such as bacteria and/or fungus can grow, and which can be difficult or impossible to adequately clean and disinfect without disassembly. This can be impermissible for food, beverage, and pharmaceutical applications. 
         [0008]    Thus, what is sought is a pinch valve, that overcomes one or more of the shortcomings and limitations set forth above, particularly, that provides effective closure under higher pressure conditions without damaging or significantly shortening the life of the tubular element and trapping fluids, and that reduces or eliminates occurrence of stretching or deformation in a manner to harbor contaminants. 
       SUMMARY OF THE INVENTION 
       [0009]    What is disclosed is a pinch valve that overcomes one or more of the shortcomings and limitations set forth above, particularly, that provides effective closure under higher pressure conditions without damaging or shortening the life of the tubular element and trapping fluids, and that reduces or eliminates occurrence of stretching or deformation in a manner to harbor contaminants. 
         [0010]    According to a preferred aspect of the invention, the valve includes a valve member that moves a pinch head laterally into a main passage of a housing or body of the valve containing the tubular element, to initially deform the tubular element from its original or free state sectional shape, e.g., round, oval, elliptical, polygonal, etc., into a generally crescent or similar shape to reduce and/or regulate flow, and then with further movement of the valve member, to deform into a generally U-shape to close and prevent flow. The pinch head preferably has a sectional shape generally the same as but a predetermined amount smaller than, an opposing inner surface bounding the main passage, and lateral or side surfaces that trail the tip or leading end of the pinch head and cooperate with opposing portions of the inner surface, to bend or fold over lateral end portions of the tubular element, that is, the opposite distal ends or legs of the U-shape. The valve member additionally includes associated laterally positioned elements, preferably in the form of pinch shoulders laterally of or adjacent to the sides of the pinch head, positioned in opposing relation to surface portions of the body or housing of the valve, and that also trail the tip or leading end of the pinch head, to contain or enclose and finally pinch the folded over lateral portions closed as the U-shape main portion of the tubular element is pinched closed, to completely prevent flow through the tubular element. 
         [0011]    As an attendant advantage, the pinching elements are preferably configured such that as the tubular element is finally fully pinched closed, any remaining fluid between the portions being pinched together is forced out, e.g. by a squeezing or squeegeeing action, so as not to be trapped and stress the sidewall of the tubular element, even at higher pressures, e.g., greater than 40 psi but less than 125 psi and the like, and at lower temperatures, such as when carrying chilled process chemicals, spirits, etc, or when used in an outdoor or refrigerated environment. To facilitate this effect, the pinch head is preferably elongate in the flow direction and has a generally convergingly tapered or oval profile shape e.g., a boat or canoe hull profile shape when viewed in the flow direction, with no cavities or other shapes along the length thereof operable to trap and retain fluid between the pinched together sections of the tubular element. 
         [0012]    According to another preferred aspect of the invention, the pinch shoulders and associated opposing surface portions can be angularly oriented in relation to a direction of movement of the valve member, as a non-limiting example, at between about a 20 degree and a 90 degree angle thereto. This can be desirable and advantageous, as the bent or folded over end portions of the tubular element that form the distal ends of the U-shape tend to form a loop at the very end, and this angularity and other shapes has been found to facilitate the smooth pinching together of the folded over portions in a manner to eliminate gaps and pockets that can trap fluid to deform, stretch, and/or weaken or perforate the sidewall. The pinch shoulders and associated adjacent sides of the pinch head can also be advantageously shaped, e.g., convex, concave, etc., and the opposing inner surfaces of the valve housing and side surfaces generally matingly shaped, e.g., concave, convex, etc., in a manner such that the folded together ends of the tubular element are pinched to remove any gaps and/or pockets. 
         [0013]    According to another preferred aspect of the invention, the pinch head is elongate in the direction of flow through the tubular element, as a non-limiting example, from about 1.5 to several times the lateral extent of width of the tubular element, so as to pinch the tubular element three dimensionally, which has been found to reduce potential for leakage and also stress concentrations. Also preferably, the pinch head is sufficiently paced from connection to fittings such as barbed fittings, clamps, and the like, so that deformation of the tubular element does not form small gaps or crevices in which fluid can be trapped so as to become contaminants during later use. 
         [0014]    As another preferred aspect of the invention, the valve member and pinch head are supported and move using a suitable actuator or drive, which as non-limiting examples, can include a threaded shaft or barrel, solenoid, servo motor, stepping motor, linear or rotary actuator, fluid cylinder, and/or a suitable mechanical linkage such as an over center or toggle mechanism, or the like, as a non-limiting example, manually operable for moving the valve member and pinch head between the open and closed positions. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a perspective view of an embodiment of a pinch valve constructed and operable according to the teachings of the invention; 
           [0016]      FIG. 2  is a side view of the pinch valve of  FIG. 1 ; 
           [0017]      FIG. 3  is a sectional side view through the pinch valve, and showing a pinch valve member of the valve in about a full open position in association with a resilient tubular element of the valve shown essentially in a free state; 
           [0018]      FIG. 4  is a sectional end view through the pinch valve taken along line  4 - 4  of  FIG. 2 , showing the pinch valve member in the full open position, and showing a pinch head and pinch shoulders of the pinch valve member in relation to the tubular element and side surfaces of a body of the valve; 
           [0019]      FIG. 5  is an enlarged sectional end view through the pinch valve with the pinch valve member in the full open position; 
           [0020]      FIG. 6  is a sectional side view through the pinch valve with the valve member in a partially closed position pinching the tubular element to restrict flow therethrough; 
           [0021]      FIG. 7  is a sectional end view through the pinch valve with the valve member in the partially closed position pinching the tubular element into a generally crescent shape, and showing cooperation of the pinch head, pinch shoulders, and side surfaces pinching folded over ends of the crescent shape tubular element; 
           [0022]      FIG. 8  is a sectional side view through the pinch valve, with the valve member in a full closed position pinching the tubular element into a generally U-shape and the pinch shoulders pinching the ends closed, to completely prevent flow through the tubular element; 
           [0023]      FIG. 9  is a sectional end view through the pinch valve with the valve member in the full closed position; 
           [0024]      FIG. 10  is a sectional end view of the pinch valve including a second embodiment of a valve member including a pinch head and pinch shoulders of a different configuration, shown in a partially closed position pinching the tubular element to restrict flow therethrough; 
           [0025]      FIG. 11  is a sectional end view of the pinch valve of  FIG. 10  with the valve member shown in a full closed position pinching the tubular element closed in a generally U-shape with folded over ends or legs of the U-shape pinched against the side surfaces of the body; 
           [0026]      FIG. 12  is a sectional end view of the pinch valve including a third embodiment of a valve member including a pinch head with pinch shoulders oriented at an acute angle to a direction of movement of the valve member, shown in a partially closed position pinching the tubular element into a generally crescent shape to restrict flow therethrough; 
           [0027]      FIG. 13  is a sectional end view of the pinch valve of  FIG. 12  with the valve member shown in a full closed position pinching the tubular element closed in a U-shape, the folded over ends or legs of the U-shape pinched closed against the side surfaces of the valve body by the pinch shoulders; 
           [0028]      FIG. 14  is a simplified schematic representation of a valve member having associated pinch shoulders facing in the direction of movement of the valve member, shown pinching a tubular element into a generally U-shape with ends of the U-shape pinched closed by the shoulders; 
           [0029]      FIG. 15  is a simplified schematic representation of a valve member having associated pinch shoulders angularly related to the direction of movement of the valve member, shown pinching a tubular element into a generally U-shape with ends of the U-shape pinched closed by the shoulders at the angular relation; and 
           [0030]      FIG. 16  is a simplified schematic representation of a valve member having a pinch head without pinch shoulders, pinching a tubular element into a generally U-shape. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Referring now to the drawings, in  FIGS. 1-9  a pinch valve  20  constructed and operable according to the teachings of the present invention is shown. Valve  20  includes a valve body  22  that is hollow and open on opposite ends to accommodate fittings  24  and  26  for attachment in fluid connection to a fluid system, such as tubes or hoses, in the well known manner, for flow of the fluid through valve body  22 , also in the well known manner. A handle  28  external to valve body  22 , connects to a threaded shaft  30  that extends into a threaded aperture  32  in a valve block  34  affixed to and forming a part of valve body  22 . All of the above described elements can be fabricated from suitable rigid material such as a metal or plastics, in the well known manner. 
         [0032]    Valve body  22  is a hollow, open ended structure including an inner surface  36  bounding and defining an open ended main passage  38  extending therethrough. A resiliently flexible, hollow tubular element  40  occupies passage  38 , and has opposite ends  42  and  44  that connect to fittings  24  and  26 , respectively. This connection can be made in any desired manner, such as, but not limited to, a friction and/or compression fit, barbs or other detents, mechanical fasteners, clamps, adhesives, and the like. 
         [0033]    Tubular element  40  can be of conventional composition and construction, e.g., poly vinyl chloride, natural rubber, synthetic rubber, silicone, neoprene, perfluoroalkoxy, polytetrafluoroethylene, and various flexible plastics, etc., that can be repeatedly pinched closed and rebound to an open shape, either automatically or when pressurized fluid is present therein, and can comprise consumer or utility grade, food grade, and/or pharmaceutical grade tubing, as desired or required for a particular application. Tubular element  40  can also be provided in any desired cross sectional shape, such as a round, oval, or polygonal shape, in any diameter, as desired or required. Here, it can be observed that tubular element  40  has a free state generally round shape, as a non-limiting example, and inner surface  36  has essentially the same shape and is about the same diameter. Fluid can flow through a flow passage P tubular element  40  in either direction, generally denoted by the term “flow direction” identified by double ended arrow F in  FIG. 3 . 
         [0034]    Valve block  34  is hollow and has an internal surface  46  that in combination with an inner surface portion  48  of valve body  22 , bound and define a lateral passage  50  that connects at one end with threaded aperture  32 , and at the opposite end with main passage  38  through a lateral opening  52  bounded and defined by inner surface  36  of valve body  22 . Lateral passage  50  extends in a first lateral direction denoted by arrow A away from main passage  38 . Lateral passage  50  and lateral opening  52  each have a generally rectangular shape when viewed in the first direction, lateral passage  50  being larger than lateral opening  52  in a second lateral direction denoted by arrow B ( FIG. 5 ), extending sidewardly or laterally relative to the flow direction and the first direction, such that lateral passage  50  terminates at side surfaces  56  and  58  facing at least generally in the first direction (away from main passage  38 ) adjacent to and bounding opposite sides of lateral opening  52 . 
         [0035]    As also shown in  FIG. 5 , lateral opening  52  has a width W and lateral passage  50  has a width W 1 , which is a predetermined amount greater than width W. It can additionally be observed that lateral opening  52  has about the same dimension as the diameter or sideward extent in direction B of main passage  38  and also tubular element  40 , and that the sides of lateral opening  52  extend to about the midpoint of main passage  38 , and side surfaces  56  and  58  abut and extend sidewardly in opposite directions from the opposite sides of passage  38 . 
         [0036]    A pinch valve member  60  is disposed in lateral passage  50  for movement in a closing direction opposite the first direction A, and an opposite opening direction in direction A. Valve member  60  is movable between a full open position ( FIGS. 3-4 ), and a full closed position ( FIGS. 8 and 9 ), through a range of partially open positions ( FIGS. 6 and 7 ). Here, to accomplish this capability, valve member  60  is supported or carried on an end of threaded shaft  30  via a rotary joint  62  that allows shaft  30  to be rotated by handle  28  relative to valve member  60  in threaded engagement with threaded aperture  32 , to move the valve member in the desired closing or opening direction. As a non-limiting example, rotary joint  62  can comprise a hole in the end of member  60  that receives the end of shaft  30 , and a cross slot in member  60  that intersects the hole, and a groove about shaft  30  that receives a C-clip or other retainer about the shaft, through the cross slot, to retain the shaft in the hole. As another example, a set screw can extend into the groove about shaft  30  to retain it. 
         [0037]    Associated with valve member  54  for movement therewith are pinch shoulders  64  and  66 , disposed in side regions or portions of lateral passage  50  in opposing relation to side surfaces  56  and  58 , respectively; and a centrally located pinch head  68  that projects or extends from valve member  54  through lateral opening  52  into passage  38  so as to abut tubular element  40  when in the full open position, as illustrated in  FIGS. 4 and 5 . Here, in the full open position an endmost tip  74  of pinch head  68  is shown slightly deforming tubular element  40  from its generally round free state cross sectional shape, but it should be understood that this is not necessary and tip  74  can instead more gently abut the tubular element or not contact it at all in the full open position, as desired. Additionally in the full open position, it should be observed that pinch shoulders  64  and  66  are spaced a significant distance from tubular element  40 . Examining  FIGS. 5 through 9  it can be seen that in the transition from full open to full closed, tubular element  40  is deformed from its generally round or circular free state shape, through a range of progressively tighter or smaller crescent shapes in the range of partially open positions reducing the sectional extent of flow passage P, to a U-shape when in the full closed position, fully closing passage P. Structurally, shoulders  64 ,  66  and pinch head  68  can be of unitary construction integrated onto pinch valve member  60 , or they can comprise one or more separate elements affixed to, carried on, or otherwise configured to be movable with the valve member, as desired or required for a particular application. 
         [0038]    As shown in  FIG. 9 , pinch head  68  preferably has a rounded profile shape when viewed in the flow direction that is about the same as the profile shape of the opposing portion of inner surface  36  bounding and defining main passage  38  opposite lateral opening  52 , e.g., a semicircular or rounded shape, but the pinch head will be a predetermined amount smaller in sectional or diametrical extent than the passage so that a substantially uniform gap or space exists between sides  70  and  72  of pinch head  68  and opposing portions of inner surface  36  when pinch head  68  is in main passage  38 , and when the valve is fully closed the same gap or space will exist between tip  74  and the opposing portion of the inner surface, as will be explained, so that the tubular element is substantially uniformly pinched or compressed. In this embodiment, pinch shoulders  64 ,  66  are angularly related to sides  70  and  72  at about a 90 degree angle, respectively, and are positioned a predetermined spaced distance D from tip  74 . 
         [0039]    More particularly, valve  20  is configured such that, when in the full closed position, tip  74  will be positioned a predetermined distance D 1  from a predetermined point  82  on an opposing portion of inner surface  36  farthest from lateral opening  52 . As a result, because of the predetermined distance D to pinch shoulders  64  and  66 , the shoulders will be located a predetermined distance D 2  from point  82 . Side surfaces  56  and  58  are also about this distance from that point. In this embodiment of valve  20 , this distance relationship will place pinch shoulders  64  and  66  at least generally in abutment with side surfaces  56  and  58 , as shown, to act to pinch ends  78  and  88  as the full closed position is reached. 
         [0040]    Also in this embodiment, tubular element  40  is selected to have a sidewall thickness T ( FIG. 5 ) of a predetermined value, and distance D 1  will be equal to about twice the thickness T ( FIG. 9 ). The gap between the opposing portions of inner surface  36  and sides  70  and  72  of pinch head  68  will also be equal to about twice the thickness T, for reasons explained next. 
         [0041]    Examining  FIGS. 5-9 , it can be observed that pinch head  68  is configured, e.g., shaped, such that when valve member  60  is moved from the full open position, pinch head  68  will be driven against tubular element  40  to deform or pinch it into the progressively narrower crescent shapes as a function of the amount of movement, thereby reducing flow passage P. As best shown in  FIG. 7 , as this occurs, side or lateral end portions  78  and  80  are bent or folded over in overlaying relation, respectively, by movement of sides  70  and  72  of the pinch head into main passage  38 . As this occurs, the endmost portions of lateral end portions  78  and  80  will initially tend to have a radiused bend in the region identified by circles, and see  FIG. 16 , thus at least temporarily forming a cavity that if allowed to remain, could trap fluid and/or provide a leak path. If an incompressible fluid is trapped, tubular element  40  can be deformed, or even perforated so as to be damaged and possibly leak, and thus this is to be avoided. 
         [0042]    To avoid fluid entrapment, and reduce stress on the endmost portion of tubular element  40 , the sides of lateral passage  50  provide a relief or expansion area into which tubular element  40  can initially expand to accommodate the radiusing of the very end, and then, as valve member  60  and pinch head  68  continue movement in the closing direction, the overlaying portions of ends  78  and  80  are pinched together laterally to complete closure. As this occurs, the overall extent of tubular element  40  in the first direction is thus reduced or compacted, so as to be withdrawn from close proximity to the open side regions of passage  50  (above side surfaces  56  and  58 ). Also as this occurs, it can be observed that ends  78  and  80  are brought substantially completely between the sides of inner surface  36  and sides  70  and  72 , which are the distance D apart. As a result, all cavities within ends  78  and  80  are eliminated and any remaining fluid is removed in a manner somewhat analogous to a squeegeeing action, e.g., in the flow direction. Also as this occurs, tubular element  40  will be stretched in the region thereof generally between pinch head  68  and fittings  24  and  26 , respectively, as illustrated in  FIG. 6 , which facilitates the folding over, and thus it is realized that the deformation into the U-shape is done in a three dimensional manner, which facilitates the smooth folding over and forming of the tubular element into the U-shape. 
         [0043]    Tubular element  40  now deformed into the U-shape, is pinched completely together in overlaying relation as valve member  60  approaches and reaches the full closed position, as shown in  FIG. 9 . At this point in the movement, ends  78  and  80  are substantially contained between the side portions of inner surface  36  of the valve body, and sides  70  and  72  of the pinch head, and now shoulders  64  and  66  are positioned to finally pinch and enclose the ends, leaving no space for cavities or voids that can trap fluid. In this condition, tubular element  40  will be stretched further between pinch head  68  and fittings  24  and  26 , respectively, as illustrated in  FIG. 8 . Again, this is advantageous, as it helps to eliminate any voids or cavities and facilitates the folding of the ends, the pinch head essentially serving as a mandrel about which the tubular element is deformed. 
         [0044]    Referring also to  FIGS. 10-13 , variant embodiments of pinch valve  20  are shown. In  FIGS. 10 and 11 , body  22  of pinch valve  20  is the same, side surfaces  56  and  58  being located at distance D 2  from point  82  on surface  36 , and tip  74  of the pinch head being located the distance D 1  from that point when valve member  54  is in the full closed position as shown in  FIG. 11 . However, pinch shoulders  64  and  66  are now a distance D 3  from the end of tip  74 , which is an increase over distance D of an amount about equal to distance D 1  or twice the thickness of the sidewall of tubular element  40 . This is significant as it places pinch shoulders  64  and  66  distance D from side surfaces  56  and  58  when the valve member is in the full closed position as shown in  FIG. 11 , such that lateral end portions  78  and  80  of the pinched tubular element can now be pinched closed between pinch shoulders  64  and  66  and side surfaces  56  and  58  as shown. 
         [0045]    As explained above, as valve member  54  is moved through the partially closed positions, e.g.,  FIG. 10 , lateral end portions  78  and  80  of tubular element  40  are pinched between side surfaces  70  and  72  and the opposing portions of inner surface  36 , the endmost portions being allowed to deform or extrude into adjacent side regions  86  and  88  of lateral passage  50 . This is shown here by arrows in  FIG. 10 . Here, it can be observed that the junctures of shoulders  64  and  66  and sides  70  and  72  of pinch head  68  essentially form concavities  84  that receive and facilitate bending and directing the ends  78  and  80  laterally or sidewardly in the directions of the arrows, so as to overlay side surfaces  56  and  58  so as to be positioned to be directly pinched by pinch shoulders  64  and  66 . The junctures can be curved to facilitate the bending, if desired, and the side surfaces  56  and  58  with the adjacent sides of inner surface  36  are essentially convex in overall shape, so that, they act in cooperation with sides  70  and  72  and pinch shoulders  64  and  66  to bend ends  78  and  80  in the required manner as shown. As before, the tubular element  40  will be stretched longitudinally as valve member  60  is closed, as explained above in reference to  FIGS. 6 and 8 . 
         [0046]    In  FIGS. 12 and 13 , body  22  of pinch valve  20  is changed slightly, inner edges of side surfaces  56  and  58  being located at about the same distance from point  82  on surface  36 , and tip  74  of the pinch head being located the same distance from that point when valve member  54  is in the full closed position as shown in  FIG. 13 . However, side surfaces  56  and  58  and pinch shoulders  64  and  66  are oriented at an acute angle relative to direction A, so that lateral end portions  78  and  80  of tubular element  40  will be deformed or extruded into side regions  86  and  88 , as shown by the arrows, respectively, and then pinched together at the acute angle. Also again, pinch head  74  and pinch shoulders  64  are located a predetermined distance apart so as to be positioned twice the thickness of the sidewall of tubular element  40  apart (distance D) when valve member  40  is in the full closed position. When the ends of the tubular element are pinched together in regions  86  and  88  there is no available space for cavities or voids between the pinched together portions of the tubular element, nor a space for the endmost portions to expand into so as to provide a leak path. 
         [0047]      FIGS. 14 and 15  are simplified illustrations showing the general concept of operation of the above described valves  20  including valve members  60  with pinch heads  74  including pinch shoulders  64  and  66  that function in cooperation with associated side surfaces  56  and  58  to deform or extrude the ends of the pinched tubular element  40 , for comparison with  FIG. 16  which shows a valve member  60  having a straight pinch head  74  without pinch shoulders and the possible outcome of looping of the ends of the pinched together tubular element  40  about the pinch head, to illustrate a problem to be avoided and an important advantage of the invention. 
         [0048]    It should be understood that the invention is intended to be used and have utility in a wide variety of applications, and can be incorporated in manually operated valves and automatically operated valves such as those operated by electrical actuators, compressed air, and vacuum. The invention can also be incorporated into valves of a variety of sizes. Still further, the pinch head can have a variety of lengths and shapes when viewed from the side, for instance, as a non-limiting example, a length of about 1.5 times larger (or greater) than its width. The ends of the pinch head can have a variety of alternative shapes, including a tapered, curved, or boat or canoe hull shape, as desired. 
         [0049]    Additionally, it should be understood that it is within the scope of the invention that pinch valves  20  can be configured in a variety of manners for different applications and regulating fluids. As a non-limiting example, the valve can be configured as a beer dispensing faucet, or a spirits or other beverage dispensing faucet, and for these application one end of the tubular element can be configured as or connect with a dispensing spout. To operate the faucet, instead of utilizing a threaded shaft and rotary joint for moving the valve member, a lever apparatus can be used. The beer will typically be pressurized, for instance, at a pressure as high as 40 psi, which pressure can spike higher, and to ensure that the faucet is not forced open from a closed condition by the pressure alone, the lever apparatus can be configured to have a mechanical advantage over the pressurized tubular element. As another non-limiting example, the lever can be weighted in a manner similar to known faucet handles. As another non-limiting example, the lever can be configured as a linkage, such as an over-center linkage or toggle linkage mechanism, operable to lock the valve member in the fully closed position and to release the valve member and retract it to a desired extent from the main passage by a simple movement of an associated lever or handle. Thus it should be understood that the pinch valve of the invention can be utilized with a variety of apparatus for supporting and moving valve member  60  between its open and closed positions, as alternatives to the threaded shaft and rotary joint discussed above. As non-limiting examples, commercially available or custom manufactured toggle or over center linkage mechanisms in connection with a smooth barrel or plunger. 
         [0050]    In light of all the foregoing, it should thus be apparent to those skilled in the art that there has been shown and described a novel pinch valve. However, it should also be apparent that, within the principles and scope of the invention, many changes are possible and contemplated, including in the details, materials, and arrangements of parts which have been described and illustrated to explain the nature of the invention. Thus, while the foregoing description and discussion addresses certain preferred embodiments or elements of the invention, it should further be understood that concepts of the invention, as based upon the foregoing description and discussion, may be readily incorporated into or employed in other embodiments and constructions without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown, and all changes, modifications, variations, and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims which follow.