Abstract:
A rotary valve adapted for injection of a fluid sample into a flow path. According to the invention one and the same valve can be used to input flow from a system pump, a sample pump and a syringe. A loop could be filled from both the sample pump and the syringe and the loop can be emptied by the system pump whereby for example a column is filled. Furthermore the sample pump can be used to pump directly to the column.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a filing under 35 U.S.C. §371 and claims priority to international patent application number PCT/SE2008/000111 filed Feb. 11, 2008, published on Aug. 28, 2008, as WO 2008/103098, which claims priority to patent application number 0700462-5 filed in Sweden on Feb. 22, 2007. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to valves and more specifically to rotary valves used to introduce a sample into the flow path of an analytical or preparative instrument, such as a liquid chromatography system (LCS). 
       BACKGROUND OF THE INVENTION 
       [0003]    Valves are commonly used in devices that involve the transportation of a fluid. A typical type of valve, for example used in laboratory systems of moderate sizes, is the rotary valve. 
         [0004]    Generally, a rotary valve has a stationary body, herein called a stator, which co-operates with a rotating body, herein called a rotor. 
         [0005]    The stator is provided with a number of inlet and outlet ports. The ports are via bores in fluid communication with a corresponding set of orifices on an inner stator face. The inner stator face is an inner surface of the stator that is in fluid tight contact with an inner rotor face of the rotor. The rotor is typically formed as a disc and the inner rotor face is pressed against the inner stator face in rotating co-operation. The inner rotor face is provided with one or more grooves which interconnect different orifices depending on the rotary position of the rotator with respect to the stator. 
         [0006]    Rotary valves can be designed to withstand high pressures (such as pressures above 30 MPa). They can be made from a range of materials, such as stainless steel, high performance polymeric materials and ceramics. 
         [0007]    The number of inlets/outlets as well as the design of grooves in the rotor or the stator reflects the intended use of a specific valve. 
         [0008]    A common type of multi-purpose valve has one inlet port (typically placed in the rotary axis of the valve) and a number of outlets ports that are placed equidistantly around the inlet port. The rotor has a single, radially extending groove that has one end in the rotary centre, thereby always connecting to the inlet, while the other end connects to any one of the outlets depending on the angular position of the rotor with respect to the stator. Such a valve is useful to direct a flow from the inlet to any of the outlets—one at a time. 
         [0009]    More complicated arrangements, tailor-made to perform one or several specific tasks, are possible. For instance, rotary valves may be used to introduce a fluid sample into the fluid path of an analytical system. 
         [0010]    A typical example of such a valve is the INV-907 valve available from GE Healthcare. A schematic illustration of this valve is provided in  FIG. 1 to 3 . The valve  20  has a first inlet  1  for connection to a liquid source (such as a pump), a second inlet  2  for introduction of a sample (typically using a syringe or a dedicated sample pump), a third inlet  3  and a first outlet  4  to/from a device for temporary storage of the fluid sample such as a retaining capillary loop  22  (well known within the art), and a second outlet  5  that connects the valve to the downstream part of the analytical or preparative system e.g. an ÄKTA™explorer system available from GE Healthcare. In addition, the valve has two waste outlets  6 ,  7  to allow a fluid to exit the valve directly to waste. 
         [0011]    The orifices of the inner stator face of the INV- 907  are represented by circles in  FIG. 1-3 , such as the circle  23  in the  FIG. 2 . In addition, a groove  24  is provided in the inner stator face. 
         [0012]    In the figures, the rotor is represented by its grooves  25 ,  26 ,  27 . When the rotor is rotated, the grooves change positions with respect to the inner stator face, thus enabling new flow paths through the valve. 
         [0013]      FIG. 1  shows a “load position”, wherein a sample may be introduced via the rotor groove  25  into the capillary loop  22  for temporary storage. At the same time the pump can provide a flow through the remaining system via the rotor groove  27 . In this position, the stator groove  24  forms a small cul-de-sac. 
         [0014]      FIG. 2  shows an “inject position”, wherein the valve is now rotated 45° to allow the capillary loop  22  to form a part of the overall flow path of the system. The pump forces, via stator groove  24  and rotor grooves  27  and  25 , the sample out of the capillary loop into the system for any separation, detection or other feature provided by the system. In this position, a part of the groove  27  forms a small cul-de-sac. 
         [0015]      FIG. 3  shows a “waste position”, allowing the pump to direct fluid directly to a waste outlet via rotor groove  27 . 
         [0016]    As mentioned above, the sample may be introduced either with a syringe or a dedicated sample pump. Using a conventional injection valve, for example of the type shown, requires that the sample pump is connected to the port that alternatively should be used for the syringe, i.e. both alternatives could not be used at the same time. 
         [0017]    Therefore the user has to re-plumb the system to alternate between these operative modes which reduce the flexibility of the system. 
       SUMMARY OF THE INVENTION 
       [0018]    An object of the invention is to provide a sample injection valve that is more flexible for the user. 
         [0019]    This is achieved in a rotary valve according to claim  1  of the present application. 
         [0020]    Hereby a sample injection valve is achieved which allows sample to be applied both by hand (for instance using a syringe) or automatically (such as by using a dedicated sample pump). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a schematic view of a prior art introduction valve in a load position. 
           [0022]      FIG. 2  shows the valve of  FIG. 1  in an inject position. 
           [0023]      FIG. 3  shows the valve of  FIG. 1  in a waste position. 
           [0024]      FIG. 4  is a schematic side view of a rotary valve. 
           [0025]      FIG. 5  shows the front side of a valve stator according to one embodiment of the invention. 
           [0026]      FIG. 6  shows the inner stator face of the stator of  FIG. 5 . 
           [0027]      FIG. 7  shows the angular distribution of the orifices in the inner stator face according to one embodiment of the invention. 
           [0028]      FIG. 8  shows the inner rotor face of a rotor according to one embodiment of the invention. 
           [0029]      FIG. 9  shows the positions of the grooves in the inner rotor face according to one embodiment of the invention. 
           [0030]      FIG. 10  is a schematic view of a first rotor position. 
           [0031]      FIG. 11  is a schematic view of a second rotor position. 
           [0032]      FIG. 12  is a schematic view of a third rotor position. 
           [0033]      FIG. 13  is a schematic view of a fourth rotor position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    The main parts of a typical rotary valve  10  are schematically shown in  FIG. 4  (wherein no brackets or similar load carrying or fastening elements are shown). The rotary valve  10  has a stator  11 , a rotor  12 , a rotary shaft  13  that optionally may be provided with means (not shown) for recognizing its angular position and a driving unit  14  typically comprising a gear box and a motor (although a valve also may be operated manually). The rotor is rotatable with respect to the stator around a rotary axis RA of the valve. 
         [0035]    The stator  11 , which is fixed with respect to the instrument into which it is built, is provided with ports (not shown in  FIG. 4 ) for fluid communication with a fluid source and any components with which the valve is to co-operate. The ports may be positioned on any suitable position on the exterior surface of the stator. The ports are provided with means to connect capillaries or tubing. Such means may be of any suitable type, such as conventional Valco fittings well known to anyone skilled in the art. The ports are via channels in fluid communication with a corresponding set of orifices on an inner stator face  11   a,  i.e. that surface of the stator  11  that during operation is in contact with the rotor  12 . 
         [0036]    The rotor  12  is typically formed as a disc and has an inner rotor face  12   a  that is that face that is pressed against the inner stator face  11   a  during operation. The inner rotor face  12   a  is provided with one or more grooves which interconnect different orifices of the inner stator face  11   a  depending on the rotary position of the rotor  12  with respect to the stator  11 . 
         [0037]      FIG. 5  shows a simplified perspective view of the front side of a stator  11  according to one embodiment of the invention. The front side is here the side of the stator  11  opposite the inner stator face  11   a.  Inlet and outlet ports  31   a - 38   a  are illustrated. 
         [0038]    Generally, it should be noticed that the angular position of ports, grooves and similar shown in the figures of the present application could differ between different embodiments of the invention, i.e. they could be turned with respect to the rotary axis of the valve, mirrored or altered in other ways as long as their mutual co-operation is still according to the inventive idea. 
         [0039]    In addition, since the inlet/outlet ports in the stator are connected to orifices on the inner stator face  11   a  via bores (or any type of channels) it is possible to arrange the ports in a way that differs from the pattern of orifices on the inner stator face  11   a  by making non-linear channels between the ports and the orifices. The ports into the stator can even be positioned on another outer surface of the stator than the front side. However, for reasons of simplicity, the ports are shown as being positioned in-line with the inner stator face orifices as will be described below in relation to  FIG. 6 . 
         [0040]    Thus, the stator  11  according to one embodiment of the present invention has eight ports  31   a - 38   a  that are used to connect the valve to all desired operative components of the instrument. According to other embodiments of the invention one or more additional orifices and ports can be provided to give some additional features to the valve. 
         [0041]    Port  31   a  is called a first inlet port  31   a.  It is positioned essentially in the middle of the stator and is used as inlet port from a main liquid source of the instrument, such as a pump, herein called the system pump. In the case of a Liquid Chromatography System, LCS, the system pump provides a flow of a single, so called buffer liquid or, alternatively, a fixed or variable mixture of two or more buffer liquids. Port  34   a  is called a first outlet port  34   a  and serves as the outlet port from which the liquid is allowed to exit to the remaining part of the instrument. 
         [0042]    A retaining loop, such as a conventional capillary loop for use in a LCS, is in this embodiment connected at one end to a first connection port  32   a  and at the other end to a second connection port  35   a.    
         [0043]    Two ports  36   a,    37   a,  here called second and third inlet ports  36   a,    37   b  are provided for introduction of a sample. In the preferred embodiment shown, the third inlet port  37   a  is intended for manual sample injection, typically using a syringe, while the second inlet port  36   a  is intended to be connected to a dedicated sample pump. The sample pump may be integrated in the instrument, or it may be a stand-alone device. 
         [0044]    The ports  33   a  and  38   a  are called second and third outlet ports  33   a  and  38   a  and are in this embodiment waste outlet ports. 
         [0045]      FIG. 6  is a perspective view of the stator  11  of  FIG. 5  viewed from the other side, i.e. the inner stator face side  11   a.  Note that each port is connected to the inner stator face  11   a  via a channel ending in an orifice  32   b - 38   b  shown in the figure. For reason of simplicity, the orifice with number  32   b  is connected to the port with number  32   a  and so on. 
         [0046]    In addition to the orifices connected to the ports, a stator groove  39  is in this illustrated embodiment provided in the inner stator face  11   a.  The stator groove  39  is typically of the same width as an orifice diameter. It should be noted that although the stator groove  39  is preferred in order to allow the system pump to pump liquid through the system while the sample pump fills the loop (this will be described in detail below), it is not essential for the inventive idea. Without the stator groove  39  the system pump must either be at still when the sample pump fills the loop or there should be an additional waste outlet provided in the stator. For example another waste outlet may be provided between the second connection orifice  35   b  and the second inlet orifice  36   b.    
         [0047]    Looking at the inner stator face  11   a,  the general angular distribution of the orifices and the ends of the groove  39  for one embodiment of the invention is illustrated in  FIG. 7 . The positions for orifices, groove ends (and not used positions) are here shown to be equally distributed around the center of the stator (which center coincides with the rotary axis of the valve). As described above the positions of the orifices can be varied slightly without departing from the inventive idea. Since there are  12  such positions on the stator according to this embodiment, the partition angle a is 30° in this embodiment. All these positions are placed with essentially the same radial distance R to the rotational axis of the valve. 
         [0048]    The inner rotor face  12   a  of the rotor  12  of a valve embodiment according to the present invention is shown in  FIG. 8 . It is provided with five grooves, called the first, second, third, fourth and fifth groove  41 - 45 . The mutual positions and shapes of the grooves are more clearly illustrated in  FIG. 9 . 
         [0049]    Each groove has both its ends ending at essentially the same radial distance R from the center, except for one end of groove  42  that ends in the center of the inner rotor face  12   a  (coinciding with the rotary axis of the valve). Of course, the radial distance R for the rotor is the same as the corresponding radial distance R of the stator. The first groove  41  extends over an angle α, which in the present embodiment is 30°. The second groove  42  is a straight groove from the center of the inner rotor face  12   a  out towards the rim, with a length of R, and is parted from the nearest end of the first groove  41  by the angle α. The third groove  43  begins at a position parted by the angle α from second groove  42 , and ends at a position that is separated from the start position by an angle of 3 α. It is bent inwards toward the centre to form a knee  48  (or alternatively in an arcuate shape). The fourth groove  44 , which occupies angle α, is equidistantly placed between the ends of groove  43 . The fifth groove  45  has a shape similar to that of the third groove  43  (with a knee  47  displaced inwardly towards the center) but the end points are parted by an angle of 2 α, and begins at an angle α from the closest end of the third groove  43 . 
         [0050]    When assembled, the inner rotor face  12   a  is pressed against the inner stator face  11   a  in a manner that is typical for any conventional rotary valve (which is well known for anyone skilled in the art, and will not be explained herein). Depending on the mutual angular positions of the rotor  12  and the stator  11  different operation modes are obtained for the valve. These are illustrated in  FIG. 10-13 , wherein the grooves of the rotor are indicated by thick lines. 
         [0051]    In the first rotor position, as shown in  FIG. 10 , the valve allows two separate flow paths. 
         [0052]    Fluid entering the first inlet orifice  31   b,  typically from a pump, such as a system pump of a LCS, and of course through the first inlet port  31   a,  is allowed to pass through the valve via the second groove  42  and out of the first outlet orifice  34   b  and further out through the first outlet port  34   a.  In the case of a LCS, the first outlet port  34   a  is intended to be connected to the main operative components of the instrument such as a chromatography column and monitoring devices such as UV monitors. In  FIGS. 10-13  grooves and orifices are shown and referred to and it is understood that each of said orifice mentioned is connected to a corresponding port as described above. 
         [0053]    At the same time it is possible to temporarily store a sample in a capillary loop  50  (or any device with a corresponding function) by introducing it through the third inlet port  37   a.  This is typically done with a syringe. After entering the third inlet port  37   a  and further through the third inlet orifice  37   b,  the sample passes the third groove  43  to enter the loop  50  via the second connection orifice and port  35   b  and  35   a.  The loop  50  is connected to the second connection port  35   a  and at its other end to the first connection port  32   a.  Hereby fluid in the loop is allowed to exit to waste via the first groove  41  and the second outlet orifice and port  33   b  and  33   a.    
         [0054]    The other orifices, ports and grooves of the valve are not active in the first rotor position. 
         [0055]    The second rotor position, as shown in  FIG. 11 , is obtained by rotating the rotor an angle of 2×α counterclockwise (as seen from the view of  FIG. 10 ) with respect to the first rotor position and allows two separate flow paths. 
         [0056]    The fluid that enters through the first inlet port orifice  31   a,    31   b  will now pass through the valve via the second groove  42  and into the loop  50  via the first connection orifice and port  32   b,a.  Thus, the content of the loop will be forced into the main operative components of the instrument via the second connection port and orifice  35   a,    35   b,  the fourth groove  44  and the first outlet orifice and port  34   b,a.  It should be noted that the sample is expelled using an opposite flow direction through the loop  50  with respect to how it was loaded, thus allowing it to travel the shortest possible way which is beneficial since it reduces the sample dilution to a minimum. 
         [0057]    At the same time a flow from a dedicated sample pump connected to the second inlet port  36   a  may be pumped to waste via the fifth groove  45  and the third outlet orifice and port  38   b  and  38   a.  This is useful for rinsing the tubing of the sample pump, as well as for rinsing the fifth groove  45 . 
         [0058]    The other ports and grooves of the valve are not active in the second rotor position. 
         [0059]    The third rotor position, as shown in  FIG. 12 , is obtained by rotating the rotor an angle of 4×α counterclockwise (as seen from the view of  FIG. 10 ) with respect to the first rotor position. As for the first and the second position, the third rotor position allows two separate flow paths through the valve. 
         [0060]    The fluid that enters through the first inlet port and orifice  31   a  and  31   b  will pass through the valve via the second rotor groove  42 , the stator groove  39 , the third rotor groove  43  and out of the valve via the first outlet orifice and port  34   b  and  34   a  into the main operative components of the instrument as described above. This allows these grooves to be rinsed at the same time as a flow can be provided to the main operative components of the instrument. However, as mentioned above, it is possible to replace the groove  39  with a waste outlet at the end position of the second groove  42 , or even a dead-end. However, in these cases no flow will be available through the main operative components of the system. 
         [0061]    At the same time it is possible to temporarily store a sample in the capillary loop  50  by introducing it through the second inlet port and orifice  36   a  and  36   b.  This is preferably done with a dedicated sample pump, as is well known in the art of liquid chromatography. After entering the second inlet orifice  36   b  the sample passes the fifth groove  45  to enter the loop  50  via the second connection orifice and port  35   b  and  35   a.  At its other end the loop  50  is connected to the first connection port  32   a  to allow fluid in the loop to exit to waste via the first connection orifice  32   b,  the fourth groove  44  and the second outlet orifice and port  33   b  and  33   a.    
         [0062]    The other ports, orifices and grooves of the valve are not active in the third rotor position. 
         [0063]    Emptying of the loop  50  is performed using the second rotor position, as described above. 
         [0064]    In this described embodiment also a fourth rotor position, as shown in  FIG. 13 , is useful, although not necessary for the inventive use of the valve. The fourth rotor position is obtained by rotating the rotor an angle a counterclockwise (as seen from the view of  FIG. 10 ) with respect to the first rotor position. 
         [0065]    In the fourth rotor position, the fluid that enters through the first inlet port and orifice  31   a  and  31   b  will pass directly to the waste outlet via the second rotor groove  42  and the second outlet orifice and port  33   b  and  33   a.  This position may be used in a case when it is desired to run the main pump of the instrument without forcing any fluid through the main operative components of the instrument downstream of the valve. 
         [0066]    As described above the exact position of the orifices need not to be according to the embodiment described above. What is important for the invention is that the different grooves reaches the specific orifices that should be reached in each rotation position described above.