Abstract:
A vial autosampler includes a gripper mechanism having an actuator, a first jaw, and a second jaw. The first and second jaws are coupled to the actuator. At least one of the first and second jaws includes a magnet disposed therein. Upon energization of the actuator, the first and second jaws are urged in a first direction which energization opposes the magnetic urging of the magnets.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the priority of earlier filed co-pending provisional patent application Nos. 60/188,665, filed Mar. 11, 2000 and entitled IMPROVED VIAL HANDLING SYSTEM; and 60/188,269 filed Mar. 10, 2000 and entitled WATER AND SOIL AUTOSAMPLER. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to vial autosamplers of the type used for laboratory automation. More specifically, the present invention relates to vial handling within the vial autosampler.  
           [0003]    Vial autosamplers are used to automate laboratory analysis associated with gas chromatography, carbon measurement (total carbon and total organic carbon) as well as other types of analyses. Typically, a vial autosampler has a storage area adapted to hold a number of vials to be analyzed. A robotic system of some sort, such as a robotic arm, generally grasps the vials from the storage area and transports them to an analytical site. Once transported to the analytical site, the vial contents are sampled and the appropriate analysis is performed.  
           [0004]    With the advent of laboratory automation, efficiencies have been greatly improved. One of the main reasons for such efficiency is the automatic nature of such machines which is provided by their various robotic systems. Such robotic systems are not without their own costs however. While efficiency may be increased by use of robotics, the cost of a given laboratory automation machine, such as a vial autosampler is almost always increased. Therefore, the provision simplification of robotic complexity work also reduces system complexity as well.  
           [0005]    In the design of automated vial handling systems, vial gripper design is very important. The contents of a given vial may represent significant analytical effort, and if a vial is mishandled, the efforts may be lost. It is important that the vial be gripped with sufficient force to ensure that it will not drop during transport and delicately enough such that damage to the vial does not occur. Moreover, it is important that in the event of power failure, the gripper does not suddenly open and allow the vial to drop.  
           [0006]    Another technical challenge is due to automatic vial autosamplers that store a number of vials in a rectangular matrix. Thus, a gripper must be able to effectively select and transport any given vial, even though the vials may be disposed relatively closely together.  
         SUMMARY OF THE INVENTION  
         [0007]    A vial autosampler includes a gripper mechanism having an actuator, a first jaw, and a second jaw. The first and second jaws are coupled to the actuator. At least one of the first and second jaws includes a magnet disposed therein. Upon energization of the actuator, a first and second jaws are urged in a first direction which energization opposes the magnetic urging of the magnets. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a perspective view of an illustrative automatic vial handling system with which embodiments of the present invention are useful.  
         [0009]    [0009]FIGS. 2A and 2B are top plan and side elevation views, respectively, of a gripper mechanism in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0010]    [0010]FIG. 1 shows a perspective view of a vial autosampler device  10  in accordance with the invention. The device  10  includes a base unit  12  that includes a vial storage platform area  14 , a sampling station  20 , and a fluid handling system comprising valves, glasswork, an other fluid handling components. Sampling station  20  receives a vial containing a specimen and extracts a fluid from the vial for further analysis. Finally, device  10  includes a central programmable control circuit that accepts user inputs and controls the operation of device  10 .  
         [0011]    [0011]FIGS. 2A and 2B are top plan and side elevation views, respectively, of an improved gripper mechanism for use with a vial autosampler. The gripper mechanism illustrated in FIGS. 2A and 2B is preferably mounted upon a robotic arm that is adapted to transport vials from vial storage area  14  to the vial analysis site(s).  
         [0012]    Gripper mechanism  500  includes actuator  502  and jaws  504  and  506 . Although gripper mechanism  500  will be described with respect to two jaws, it is contemplated that more than two jaws could be used. It is preferred that jaws  504  and  506  are constructed from a lightweight non-magnetic material. Suitable examples of such material include aluminum and plastic. Although actuator  502  will be described with respect to a specific actuator embodiment, it is to be understood that actuator  502  can be any device capable of moving jaws  504  and  506  with respect to each other. Thus, actuator  502  can be an electric solenoid, an air cylinder, or any other suitable device. As shown, however, actuator  502  includes a rotary DC motor  508  that preferably operates on  24  volts DC. Motor  508  is preferably mounted to mounting block  510  such that shaft  512  passes through block  510  and is adapted to rotate with respect thereto. Shaft  512  is coupled to drive rods  514 ,  516  by pin  518 . Pin  518  contacts drive rods  514 ,  516  such that rotation of pin  518 , as indicated by arrows  520 , translates drive rods  514  and  516  in the directions of arrows  522  and  524 , respectively. Since drive rod  514  is coupled to jaw  506 , and drive rod  516  is coupled to jaw  504 , rotation of pin  518  causes jaws  504  and  506  to be separated from one another. Translation of both jaws in opposite directions is important to ensure that the center point of a vial either being picked up or put down is not changed thus not causing a lateral displacement of the vial.  
         [0013]    As can be seen in FIGS. 2A and 2B, jaws  504 ,  506  are preferably coupled to drive rods  514 ,  516 , respectively, by pins  526 . However, it should be understood that one aspect of the invention is the ability to change jaws. Thus, embodiments where jaws  504  and  506  can be decoupled from drive rods  514 ,  516  are contemplated. With such interchangeable jaw embodiments, different jaws can be selected for particular vial applications. One set of jaws may be adapted to grasp smaller vials while another set is adapted for grasping larger vials. Further, jaws with different internal surface features (which features will be described later) can be selected such that one set of jaws can be adapted to apply higher force and thus lift heavier vials, while another set of jaws can be adapted to apply less pressure and thus lift more fragile vials.  
         [0014]    At least one of jaws  504  and  506  includes a magnet that is disposed in such a manner to assist with the gripping function. In the illustrated embodiment, jaws  504  and  506  include magnets  528  and  530 , respectively. Magnets  528  are preferably fixed within jaws  504  and  506  by set screws  533 . Although two magnets  528  are shown, it is expressly contemplated that embodiments can be practiced using a single magnet, as well as more than two magnets. In a single magnet embodiment, it is important to ensure that the jaw opposite the jaw with the magnet be constructed from a material that interacts with magnetic fields, such as suitable metals. Preferably, magnets  528  are powerful rare earth magnets. In the illustrated embodiment, magnets  528  are oriented with respect to one another such that opposite poles of the magnets are facing one another thereby causing magnets  528  to urge jaws  504  and  506  together. Thus, when motor  508  is energized, drive rods  514 ,  516  overpower the magnetic urging of magnets  528  to thereby open jaws  504  and  506  to grasp a vial. To close jaws  504  and  506 , motor  508  is simply de-energized, thus allowing the magnetic forces between magnets  528  to once again urge jaws  504  and  506  together closing the gripper mechanism  500  upon vial  532  (partially illustrated in FIG. 1B).  
         [0015]    Since autosampler power loss will simply de-energize motor  508  and cause magnets  528  to grip, the system can be considered fail-safe since it ensures that vial  532  is not dropped upon power loss. However, if such a fail-safe operation is not desired, it is contemplated that the orientation of magnets  528  can be changed such that they repel one another, in which case motor  508  can be reversed such that its energization will cause jaws  504  and  506  to clench together. Using magnets  528  simplifies robotic gripper control since a single energization signal having an on-condition and an off-condition can effect opening and closing jaws  504  and  506 . Further, by using magnets  528  to assist gripping provides a simpler gripper mechanism than systems which use springs. Further, the ability of magnets  528  to urge jaws  504  and  506  together without a mechanical coupling between jaws  504  and  506 , unlike a tension spring, facilitates changing to different sets of jaws since it is unnecessary to couple any sort of mechanical element, such as spring, between jaws  504  and  506 .  
         [0016]    Jaws  504  and  506  include lower portions  536  and  538 , respectively. Lower portions  536  and  538  are adapted to contact the vial and assert sufficient frictional force to prevent the vial from slipping from gripper mechanism  500  as the vial is lifted. Preferably, each lower portion is shaped semicircularly such that the lower portions envelop substantially all of the vial outer diameter. However, it is expressly contemplated that embodiments providing a number of fingers could also be used. Lower portions  536  and  538  have friction portions  540 . Friction portions  540  are formed of an incompressible or semi-compressible material which generates a relatively high level of friction with vial  532 . One example of such material is commercially available anti-slip materials, such as diamond friction tape available from McMaster-Carr Supply Company, of Chicago Ill. under catalog number 6244T11. Those skilled in the art will recognize that a number of other materials can be used for portions  540  and such embodiments are expressly contemplated. For example, it is believed that silicone rubber or urethane could be used in friction portions  540 .  
         [0017]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.