Abstract:
A pinch valve for pinching closed a tube is comprised of a linear actuator connected pivotally a pointer. The linear actuator is parallel to the tube and the end of the pointer that engages the tube is made to follow a path that is perpendicular to the tube when the valve is closed. When the pinch valve is closed, the pointer is perpendicular to, and supported by, both the linear actuator and the tube.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/245,845, filed Nov. 4, 2000. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to the field of valves and valve controllers. Pinch valves are well known to those of ordinary skill in the art. Typically, pinch valves employ a spring-loaded system. Prior art pinch valves have certain disadvantages. Over time, these pinch valves often cut into the tubing that they cooperate with. These pinch valves require power to maintain a valve held open or pinched off. The earlier designs required significant actuation power and high profiles.  
           [0003]    Accordingly, there is a need for an improved pinch valve that addresses and overcomes the disadvantages of the earlier pinch valves. In addition, it is desirable that the pinch valve provides a positive pinch-off without cutting into the tubing it cooperates with. It is also desirable the pinch valve provides an adjustable pinch-off aperture. It is further desirable that the pinch value provides a high force pinch-off while requiring low activation power, preferably about 5 watts maximum at about 5 volts, while requiring no power to hold in the valve. Furthermore, the need exists for a pinch valve that has a profile of less than about 0.700″ high, is magnetically and thermally isolated from the tubing, and allowing for non-threaded tubing to be installed and removed.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is for a pinch valve for pinching off a tube, the valve comprising a linear actuator, a moveable back piece against which pressure can be applied, and a pointer rotatably connected to the linear actuator wherein the pointer is not in contact with the tube when the pinch valve is in the open position, but is essentially perpendicular with the tube in the pinched-off position.  
           [0005]    It is also contemplated that the linear actuator may further comprise a follower. Furthermore, the linear actuator may also comprise a motor. In addition, a guide may be included for guiding the pointer. Preferably the linear actuator is essentially parallel to the tube and the pointer is perpendicular to the tube when the valve is in the closed or pinched-off position.  
           [0006]    In the preferred embodiment it is contemplated that the moveable back piece is an eccentric. Preferably, the eccentric is adjustable and is selectively moved between a minimum and maximum position which controls the amount of pinch off.  
           [0007]    A biasing spring may be provided for holding the tubing in place. It is also contemplated that more than one biasing spring may be utilized for improved stability.  
           [0008]    The aspects, features and advantages of the present invention are readily apparent from the following description of the preferred embodiments when taken in connection with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    Comprehension of the invention is facilitated by reading the following detailed description, in conjunction with the associated drawings, in which:  
         [0010]    [0010]FIG. 1 a  is the top view of the pinch valve of the present invention in the open position;  
         [0011]    [0011]FIG. 1 b  is the top view of the pinch valve of the present invention in the closed position;  
         [0012]    [0012]FIG. 2 illustrates the pinch valve of the present invention with the open and closed positions of the valve overlapping;  
         [0013]    [0013]FIG. 3 is the right side view of the pinch value of the present invention;  
         [0014]    [0014]FIG. 4 is the left side view of the pinch valve of the present invention;  
         [0015]    [0015]FIG. 5 is the front view of the pinch value of the present invention;  
         [0016]    [0016]FIG. 6 is a left side view of an alternative embodiment of the pinch value of the present invention;  
         [0017]    [0017]FIG. 7 is a bottom view of the pinch valve of the present invention;  
         [0018]    [0018]FIG. 8 a  is an alternative embodiment of the present invention illustrating the present invention being utilized as a three way valve;  
         [0019]    [0019]FIG. 8 b  shows the three way valve of FIG. 8 a  with the actuator of the valve in an alternate position. 
     
    
     DETAILED DESCRIPTION OF INVENTION  
       [0020]    Referring to FIGS. 1 a,    1   b  and  2 , there is illustrated the preferred embodiment of the present invention, which is a pinch value that is generally designated  10 . The pinch value  10  comprises a linear actuator  12 . The linear actuator generally follows the path  13 . Preferably, the linear actuator  12  is a lead screw driven by a motor  24 . The linear actuator  12  enables pressure to be applied at the pressure point  14  by pointer  16 , which actually pinches the valve closed. A pointer  16  rides on the follower  22  of the linear actuator  12  by way of a pivot  34 . The pointer  16  is guided so that the end of the pointer  16  that is going to contact the tube  18  moves along a path that is essentially orthogonal to the tube  18 , but the linear actuator  12  that drives it is roughly parallel to the tube  18 .  
         [0021]    It is contemplated by the present invention that when the tube  18  is very nearly pinched off, i.e. as the pointer  16  pinch-off point is approached, the pressure pointer  16  approaches a right angle to the tube  18  and also approaches a right angle to the actuator  12 . As will be appreciated by those skilled in the art, the mechanical advantage is tremendous at that point. Thus, the present invention provides the maximum amount of pressure at the point where the pressure is needed in order to do the final pinch off. As those skilled in the art will appreciate, the tremendous mechanical advantage of the present invention is actually contrary to what happens in a spring loaded system. In contrast, in a spring loaded system, the spring is the weakest at the point where strength is needed the most.  
         [0022]    It is contemplated by the present invention that no power is required once the valve is pinched off. The linear actuator  12  stops and binds the pointer  16  in between the pivot  34  and the tube  18  at the pressure point  14 , providing a mechanism that binds the valve  10 , thereby eliminating any power requirement to maintain the valve  10  in a closed position. Similarly, in the open position the present invention doesn&#39;t require any power. Consequently, a valve embodying the present invention doesn&#39;t impart any heat to the system except when its actually moving. Even then, that limited heat is isolated from the fluid flow itself.  
         [0023]    The present invention further employs a positive pinch off. There are not any springs involved in the system, and when the pointer  16  comes down it pinches the tube against a movable back piece  22 , preferably an eccentric  24 . By turning the eccentric  24 , the eccentric gets closer or further away from the pinch point. This enables an operator of the valve to put a piece of tubing  18  in and adjust the eccentric  24  to get the desired amount of pinch off. This minimizes the danger of cutting through the tube because no additional pressure is applied other than that pressure required to stop the fluid flow. A significant problem with earlier pinch valves is that they tend to cut through tubing. The present invention avoids this problem by providing this positive stop rather than providing a constant pressure that over time may pinch into the tube.  
         [0024]    The minimum  26  and maximum  28  positions of the eccentric  24  are shown in FIG. 2. The small hole in the center of the eccentric  24  is the pivot  30 . As the eccentric  24  is turned, it either moves to widen or lessen the distance to the pointer. The eccentric  24  may have movement along an orthogonal axis also, but that movement is coincidental. The pointer has an end portion  32  that actually pinches off the tube. Like the eccentric  24 , the pointer is in FIG. 2 illustrated in two positions.  
         [0025]    The end portion of the pointer  16  appears as an arrow on the right side of it. On the opposite end of the pointer  16  is a pivot  34 . The pivot  34 , allows the pointer  16  to pivot along the follower  22  as the valve moves from the open and closed position and back.  
         [0026]    In the preferred embodiment, the pointer  16  has a circular guide  48  at the arrow end  32 . This guide fits in channel  36  that is cut into the valve body perpendicular to the tubing  18 , and forces that end  32  of the pointer  16  to follow a path that is essentially perpendicular to the tube  18 . The guide  48  is sub-flush to the body of the valve  10  and the pointer  16  then follows in the race track shaped channel  36  that is shown stretching left to right in FIG. 2. However, other equivalents are acceptable provided that the arrow end  32  of the pointer  16  is perpendicular to the tube  18  and the linear actuator  12  in the pinch-off position.  
         [0027]    The tube  18  is placed in between the pointer  16  and the eccentric  24  so that the tube  18  would be pinched when the pointer  16  is closed, and retracted away from the eccentric  34  when the pointer  16  is up at roughly a 45 degree angle. Optionally, as is shown in FIG. 6, a leaf spring  46  is utilized to engage the tube  18  with the valve  10  to hold the tube  18  in place when the pointer is not engaging it. This spring  36  is held in place by a screw  44 . It is also contemplated that a plurality of springs  36  are suitable to increase stability.  
         [0028]    As shown in FIG. 2, it is also contemplated that the present invention may include a relief (not shown), along the axis  38 , and under the cover so that the tube  18  fits under spanning from the top of the diagram to the bottom. This feature enables a U or C shaped piece of tubing to be fit into the valve without breaking the flow.  
         [0029]    A relief not only enables a user to visually inspect the tube, but the user can bend the tube in a U shape piece, or a C shape piece, and fit it in without breaking the flow. If a user has a system that is setup and that is working and flowing, the user may not want to open up the system. With the present invention, the user does not have to install the tube  18  in this valve  10 . The user can simply loop it into a C shape, fit it over the eccentric  24  and then straighten it out so that it is oriented between the pointer  16  and the moveable back piece  22  or eccentric  24  and is retained by the spring  46 .  
         [0030]    Referring now to FIG. 5, there are illustrated notches  40 , which enable the valve units to be stacked. Mating notches  42  are visible on the bottom of the valve  10 . These can be slid on top of each other making the units stackable. In the preferred embodiment, because the actuator  12  is parallel with tube  18 , the valve  10  is really a very thin structure, much thinner than most pinch valves. It is contemplated that up to eight valves  10  may be stacked in less than six inches. The stacking feature is particularly advantageous where the user is working on experiments where it is desirable to keep the tubing as short as possible.  
         [0031]    In an alternative embodiment, as shown in FIGS. 8 a  and  8   b , the valve  10  can be operated as a 3-way valve with minor modifications. A second pointer  54  is rotating on the same path  13  as the first pointer  16  and at the same or adjacent pivot point  34 , but oriented with a separate channel (not shown), essentially parallel to the first channel  36 . This will allow the free end of the pointer  54  to be phased opposite to first pointer  16 , that is, to be in a pinch-off position when the other is in the retracted position and similarly to be in the retracted position when the other is in the pinch-off position. Thus, by extending the body of valve out and installing a second pointer  54  on the opposite side of the first pointer  16  with second guide (not shown) and a second eccentric  52 , and a second tube  50 , a three-way pinch valve is formed.  
         [0032]    [0032]FIG. 8 a  shows the operation when the pivot  34  is at position  58 . Pointer  54  is perpendicular to tube  50  and tube  50  is pinched off, while pointer  16  is retracted from tube  18 . FIG. 8 b  shows the operation when the pivot  34  is at position  56 . Pointer  16  is perpendicular to tube  18  and tube  18  is pinched off, while pointer  54  is retracted away from tube  50 .  
         [0033]    Although the invention has been described in terms of specific embodiments and applications, persons skilled in the art can, in light of this teaching, generate additional embodiments without exceeding the scope or departing from the spirit of the claimed invention. Accordingly, it is to be understood that the drawing and description in this disclosure are proffered to facilitate comprehension of the invention, and should not be construed to limit the scope thereof.