Abstract:
A sample cooling device is provided with, inside a sample storage which stores therein a sample rack, a first heat transfer member arranged at a position in contact with the sample rack, a second heat transfer member which cools the inside of the sample storage, and a condensate discharge mechanism which discharges condensate condensing on the second heat transfer member to the outside of the sample storage. An internal space of the sample storage is not sealed due to the existence of a leak path for air formed between the inside and the outside of the sample storage, the leak path including at least the channel. The sample storage includes an outside air introduction unit which forcibly blows the outside air into the internal space so that the pressure inside the sample storage becomes higher than the outside pressure thereof. The position and the direction of an outside air outlet of the outside air introduction unit inside the sample storage are set so that the outside air blown into the sample storage directly heads for the second heat transfer member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a sample cooling device which cools a sample before analysis in an analyzer such as a liquid chromatograph analyzer. 
         [0003]    2. Description of the Related Art 
         [0004]    A sample cooling system of a sample cooling device which cools a sample before analysis includes a direct cooling system and an air cooling system. In the direct cooling system, a sample rack in which a sample container which stores therein a sample is set is placed on a sample rack placing unit that has been cooled to thereby directly cool the sample container through the sample rack (see Japanese Unexamined Patent Application Publication No. 2000-74802 and Japanese Unexamined Patent Application Publication No. 2001-12839). In the air cooling system, air inside a sample storage is cooled and circulated by a cooling Peltier element to thereby cool the entire air inside the sample storage (see Japanese Unexamined Patent Application Publication No. 2005-233867). The sample rack placing unit of the direct cooling system includes a sample rack cooling plate for directly placing and cooling the sample rack thereon, a Peltier element which cools the sample rack cooling plate, a heat dissipation fin which dissipates heat from the Peltier element, and a heat insulating material which blocks thermal conduction from components other than the Peltier element. The sample rack cooling plate is placed inside the sample storage, and the heat dissipation fin is placed outside the sample storage. 
         [0005]    Since the direct cooling system can directly cool only the sample rack, the time required to reach a desired cooling temperature is advantageously short (that is, the cooling efficiency is excellent). However, on the other hand, since only the sample rack is cooled, moisture contained in the air inside the storage condenses on the cooled sample rack. In order to prevent such a problem, a dehumidification mechanism is provided. In the dehumidification mechanism, another Peltier element (hereinbelow, referred to as a dehumidification Peltier element) is provided to forcibly cause the moisture contained in the air inside the storage to condense on a dehumidification cooling plate which is cooled by the dehumidification Peltier element. Further, the condensate is collected in a tray, and the collected condensate is discharged to the outside of the storage through a tube or the like to thereby dehumidify the air inside the storage. 
         [0006]    Such a sample cooling device includes one that constitutes a sample injection device of an analyzer such as a liquid chromatograph analyzer and one that is used for storing a sample separately from the sample injection device. The present invention is directed to both of the sample cooling devices. 
         [0007]    The sample cooling device is designed so that the airtightness inside the storage of the device becomes as high as possible in order to prevent condensation in a sample rack cooling unit. However, when the sample cooing device constitutes the sample injection device, a mechanism that moves and cleans a sampling needle for sample injection is provided inside the storage of the device. Therefore, inside the storage are formed: a hole for discharging therethrough a cleaning liquid; a hole for discharging therethrough a leaking liquid; and a gap as a leak path such as a notch for passing therethrough a channel pipe or a wire. The leaking liquid is generated, for example, when a channel switching valve for introducing a sample for analysis into an analysis channel is exhausted, and the leakage of a mobile phase solvent thereby occurs. 
         [0008]    Also in the sample cooling device that does not constitute the sample injection device, an outlet through which condensate condensing on the dehumidification cooling plate (heat transfer member) which is cooled by the dehumidification Peltier element is discharged to the outside of the storage serves as the leak path. 
         [0009]    The inside of the storage of the sample cooling device communicates with the outside air through such a leak path, and therefore, cannot be completely sealed. Therefore, even when the dehumidification mechanism operates, the outside air flows into the storage from the outside thereof through the leak path, and the humidity inside the storage thereby increases. As a result, condensation may occur in the sample rack cooling unit, the sample rack, and the sample container. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is directed to prevent the occurrence of condensation in a sample container due to the outside air flowing into a storage from the outside thereof through a leak path. 
         [0011]    In the present invention, the pressure inside a storage is made to be a positive pressure that is higher than the outside pressure thereof by forcibly introducing the outside air into the storage, thereby preventing the outside air from flowing into the storage from the outside thereof through a leak path. In addition, in order to remove moisture contained in the outside air flowing into the storage, the outside air is allowed to directly head for a dehumidification heat transfer member. 
         [0012]    Specifically, according to one aspect of the present invention, a sample cooling device includes: a sample storage which stores therein a sample rack, the sample rack holding a sample container in which a sample is put; a first temperature regulation mechanism which includes a first heat transfer member arranged at a position in contact with the sample rack stored inside the sample storage and a first cooler which cools the sample rack to a temperature equal to or lower than a room temperature through the first heat transfer member; a second temperature regulation mechanism which includes a second heat transfer member arranged at a position separately from the first heat transfer member inside the sample storage and a second cooler which cools the inside of the sample storage to a temperature equal to or lower than a room temperature through the second heat transfer member; and a condensate discharge mechanism which includes a condensate collection tray arranged at a position for collecting condensate condensing on the second heat transfer member and a channel for discharging therethrough the condensate collected in the condensate collection tray to the outside of the sample storage. 
         [0013]    An internal space of the sample storage is not sealed due to the existence of a leak path for air formed between the inside and the outside of the sample storage, the leak path including at least a channel for discharging therethrough condensate to the outside of the sample storage. Further, the sample storage includes an outside air introduction unit which forcibly blows the outside air into the internal space so that the pressure inside the sample storage becomes higher than the outside pressure thereof. The position and the direction of an outside air outlet of the outside air introduction unit inside the sample storage are set so that the outside air blown into the sample storage directly heads for the second heat transfer member. 
         [0014]    According to one aspect of the present invention, the sample cooling device constitutes a sample injection device. In such a case, the sample cooling device includes a sample inlet of an analyzer, a sampling needle which sucks a sample from a sample container held in the sample rack and injects the sample into the sample inlet, and a cleaning liquid discharge port for discharging therethrough a cleaning liquid used for cleaning the sampling needle. The sample inlet, the sampling needle, and the cleaning liquid discharge port are arranged inside the sample storage. Further, the leak path also includes an outlet of the cleaning liquid discharge port. 
         [0015]    In order to allow the outside air blown into the sample storage to directly head for the second heat transfer member, the sample cooling device preferably includes a guide plate which directs the outside air blown into the sample storage through the outside air outlet to the second heat transfer member. 
         [0016]    Further, in order to allow the outside air blown into the sample storage to directly head for the second heat transfer member, it is also preferred that the second heat transfer member include a plurality of metal plates which are arranged in parallel to the flow of the outside air blown into the sample storage through the outside air outlet. 
         [0017]    The outside air introduction unit is required to have an air feeding mechanism for blowing the outside air into the internal space. As an embodiment, the outside air introduction unit may be provided with a dedicated air feeding mechanism. 
         [0018]    On the other hand, Peltier elements may be used as the first cooler and the second cooler. When using the Peltier elements, heat dissipation fins for the respective Peltier elements and air feeding mechanisms for feeding air for heat dissipation to the respective heat dissipation fins are provided outside the sample storage. Therefore, as another form of the air feeding mechanism for blowing the outside air into the internal space, either one of the air feeding mechanisms for the respective heat dissipation fins can also serve as the air feeding mechanism for blowing the outside air into the internal space. By using one air feeding mechanism for two purposes in this manner, it is possible to simplify the configuration of the sample cooling device to thereby reduce a cost thereof. 
         [0019]    In the present invention, even with the structure in which the internal space of the sample storage is not sealed, the pressure inside the sample storage becomes a positive pressure by providing the outside air introduction unit. As a result, the inflow of the outside air into the sample storage from the outside thereof through the leak path is reduced. 
         [0020]    Further, since the position and the direction of the outside air outlet of the outside air introduction unit are set so that the outside air blown into the sample storage directly heads for the second heat transfer member, the outside air flowing into the sample storage is immediately dehumidified by the second heat transfer member. Therefore, the humidity inside the sample storage does not increase. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a schematic cross-sectional view illustrating an embodiment; 
           [0022]      FIG. 2  is a schematic cross-sectional view illustrating an example of a mechanism for blowing the outside air into a sample storage through an outside air introduction unit in an embodiment; and 
           [0023]      FIG. 3  is a schematic perspective view illustrating a dehumidification cooling plate and a guide plate in an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    An embodiment of the present invention is illustrated in  FIG. 1 . 
         [0025]    A sample cooling plate  4  as a first heat transfer member is provided in a lower part of a sample storage  2 . A sample rack  6  is placed on the sample cooling plate  4 . A plurality of sample containers, each of which stores therein a liquid sample, are put into the sample rack  6  in an aligned manner. Each of the sample containers is, for example, a small bottle made of glass. A sample rack insertion port  8  is provided on the front of the sample storage  2  (the left side in the drawing) for inserting and taking out the sample rack  6  into and from the sample storage  2 . The sample rack insertion port  8  is closed by an openable/closable lid  10 . The sample rack  6  is made of, for example, aluminum in order to improve the thermal conductivity thereof, and has a plurality of holes for inserting thereinto the sample containers. 
         [0026]    In order to cool the sample rack  6  which is placed on the sample cooling plate  4 , a Peltier element  12  as a first cooler is provided in contact with the sample cooling plate  4 . In order to dissipate heat of the Peltier element  12 , a heat dissipation fin  14  is provided outside the sample storage  2 . In order to feed air to the heat dissipation fin  14  for heat dissipation, the heat dissipation fin  14  is arranged inside a duct  16 , and a fan  18  for air feeding is provided in the duct  16 . 
         [0027]    In order to control the temperature of the sample cooling plate  4 , a temperature regulation circuit  20  and a temperature sensor  22  are provided. The temperature sensor  22  is embedded in the sample cooling plate  4  or attached in contact with the sample cooling plate  4  in order to detect the temperature of the sample cooling plate  4 . The temperature regulation circuit  20  takes in a temperature detected by the temperature sensor  22 , and controls the amount of current supplied to the Peltier element  12  so that the sample cooling plate  4  has a predetermined temperature. 
         [0028]    The sample cooling plate  4 , the Peltier element  12 , the heat dissipation fin  14 , the temperature regulation circuit  20 , and the temperature sensor  22  together constitute a first temperature regulation mechanism. 
         [0029]    A dehumidification cooling plate  24  as a second heat transfer member is arranged at a position separately from the sample cooling plate  4  inside the sample storage  2  in order to remove moisture contained in the air inside the sample storage  2 . Although the dehumidification cooling plate  24  is arranged on the right side inner surface of the sample storage  2  in the drawing, the position of the dehumidification cooling plate  24  is not particularly limited to the illustrated position. In order to cool the dehumidification cooling plate  24  to a predetermined temperature, a dehumidification Peltier element  26  as a second cooler is arranged in contact with the dehumidification cooling plate  24 . A heat dissipation fin  28  for the Peltier element  2  is provided outside the sample storage  2 . In order to feed air to the heat dissipation fin  28  for heat dissipation, the heat dissipation fin  28  is arranged inside a duct  29 , and a fan  31  for air feeding is provided in the duct  29 . 
         [0030]    In order to control the temperature of the dehumidification cooling plate  24 , a temperature regulation circuit  30  and a temperature sensor  32  are provided. The temperature sensor  32  is embedded in the dehumidification cooling plate  24  or attached in contact with the dehumidification cooling plate  24  in order to detect the temperature of the dehumidification cooling plate  24 . The temperature regulation circuit  30  takes in a temperature detected by the temperature sensor  32 , and controls the amount of current supplied to the Peltier element  26  so that the dehumidification cooling plate  24  has a predetermined temperature. 
         [0031]    The dehumidification cooling plate  24 , the Peltier element  26 , the heat dissipation fin  28 , the temperature regulation circuit  30 , and the temperature sensor  32  together constitute a second temperature regulation mechanism. 
         [0032]    Each of the sample cooling plate  4  and the dehumidification cooling plate  24  includes metal having a high thermal conductivity such as aluminum, copper, and stainless steel. 
         [0033]    The sample cooling device of the present embodiment constitutes a sample injection device which is a liquid chromatograph autosampler. Therefore, a sample inlet  35  for liquid chromatograph, a sampling needle  34  for sucking a sample from a sample container put in the sample rack  6  and injecting the sample into the sample inlet  35  for liquid chromatograph, and a cleaning liquid discharge port  36  for discharging therethrough a cleaning liquid that has been used for cleaning the sampling needle  34  are arranged inside the sample storage  2 . The sampling needle  34  is moved by a conveyance mechanism (not shown) among the positions of a predetermined sample container, the sample inlet  35 , and the cleaning liquid discharge port  36 . 
         [0034]    A pipe that communicates with the cleaning liquid discharge port  36  is led out of the sample storage  2 . In addition to the cleaning liquid discharge pipe communicating with the cleaning liquid discharge port  36 , an outlet for discharging therethrough a leaking liquid, a notch for passing therethrough a wire or a pipe, and the like serve as leak paths of the sample storage  2 . These leak paths are schematically illustrated in a collected manner as a leak path  38  in the drawings. Therefore, the leak path  38  does not indicate that only a single leak path exists on the illustrated position. In this manner, since the leak path  38  exists in the sample storage  2 , it is not possible to completely seal an internal space of the sample storage  2 . 
         [0035]    When the outside air enters the inside of the sample storage  2  through the leak path  38 , moisture is also introduced into the sample storage  2  along with the outside air. As a result, the humidity inside the sample storage  2  increases. In order to prevent such a situation, in the present embodiment, an outside air introduction unit  40  is provided in the sample storage  2  to maintain the pressure inside the sample storage  2  at a positive pressure that is higher in some degree than the atmospheric pressure around the sample storage  2 . 
         [0036]    The outside air fed through the outside air introduction unit  40  is ambient air, and therefore contains moisture. Thus, if the outside air is directly blown into the sample storage  2 , the humidity inside the sample storage  2  increases. Therefore, in the present embodiment, the position and the direction of an outside air outlet of the outside air introduction unit  40  are set so that the outside air blown into the sample storage  2  directly heads for the dehumidification cooling plate  24 . Specifically, the dehumidification cooling plate  24  is arranged on an upper part of the inner side surface of the sample storage  2 . Further, the outside air outlet of the outside air introduction unit  40  is arranged so as to face the dehumidification cooling plate  24 . In addition, a distance between the outside air outlet of the outside air introduction unit  40  and the dehumidification cooling plate  24  is set to be as short as possible, for example, set at one to several centimeters. 
         [0037]    A tray  25  which receives condensate condensing on the dehumidification cooling plate  24  is provided below the dehumidification cooling plate  24 . A tube  27  for discharging therethrough the condensate received in the tray  25  is connected to the tray  25 . An outlet of the tube  27  is also included in the leak path  38 . 
         [0038]    A heat insulating material  42  is provided between the sample cooling plate  4  and the wall surface of the sample storage  2  to achieve thermal insulation of the sample cooling plate  4 . In a direct cooling system, only the sample cooling plate  4  is required to be thermally insulated, and components other than the sample cooling plate  4  are therefore not necessarily thermally insulated. In the present embodiment, in order to improve the cooling efficiency of the dehumidification cooling plate  24 , another heat insulating material  42  is provided between the dehumidification cooling plate  24  and the wall surface of the sample storage  2 . Further, almost the entire inner surface of the sample storage  2  may be covered by a heat insulating material. 
         [0039]    In order to blow the outside air into the sample storage  2  through the outside air outlet of the outside air introduction unit  40 , the outside air introduction unit  40  is provided with a mechanism for feeding the outside air into the sample storage  2 , the mechanism being arranged outside the sample storage  2 . An example of the mechanism is a dedicated fan which is provided in the outside air introduction unit  40 . The flow rate of the outside air to be fed into the sample storage  2  through the outside air introduction unit  40  may be small as long as the pressure inside the sample storage  2  can be made to be a positive pressure that is slightly higher than the atmospheric pressure outside the sample storage  2 . Therefore, even when the dedicated fan is provided, a small fan is enough as the dedicated fan. 
         [0040]    Another example of the mechanism for blowing the outside air into the sample storage  2  through the outside air introduction unit  40  is illustrated in  FIG. 2 . This example uses the fan  31  for heat dissipation of the heat dissipation fin  28  for the Peltier element  28  as the mechanism. One end of a pipe  52  is arranged on an outlet of the duct  29 , and the other end of the pipe  52  is connected to the outside air introduction unit  40 . By virtue of the pipe  52 , a part of air flowing through the duct  29  is blown into the sample storage  2  through the outside air introduction unit  40 . 
         [0041]    Yet another example of the mechanism for blowing the outside air into the sample storage  2  through the outside air introduction unit  40  uses the fan  8  for heat dissipation of the heat dissipation fin  14  for the Peltier element  12 . In this example, one end of the pipe  52  is arranged on an outlet of the duct  16 , and the other end of the pipe  52  is connected to the outside air introduction unit  40 . 
         [0042]    A preferred embodiment of the dehumidification cooling plate  24  which promptly causes condensation of moisture contained in the outside air fed through the outside air introduction unit  40  to remove the moisture is illustrated in  FIG. 3 . The outside air outlet  40  of the outside air introduction unit  40  is arranged above the cooling plate  24  so as to face the cooling plate  24 . The cooling plate  24  includes a plurality of plates which are arranged in the vertical direction. The outside air blown into the sample storage  2  through the outside air outlet of the outside air introduction unit  40  flows downward along the cooling plate  24 . 
         [0043]    The cooling plate  24  may only be arranged in a direction that is perpendicular to the flow of the outside air blown into the sample storage  2  through the outside air outlet of the outside air introduction unit  40  in this manner. 
         [0044]    In the embodiment illustrated in  FIG. 3 , a guide plate  54  is further provided. The guide plate  54  directs the outside air blown into the sample storage  2  through the outside air outlet to the cooling plate  24 . The guide plate  54  may be a flat plate that faces the inner wall of the sample storage  2  with the cooling plate  24  interposed therebetween. In this embodiment, the guide plate  54  also includes flat plates on the respective sides of the flow of the outside air to thereby constitute a duct together with the inner wall of the sample storage  2 , the duct housing therein the cooling plate  24 . Such a guide plate  54  can forcibly direct the outside air blown into the sample storage  2  through the outside air outlet of the outside air introduction unit  40  to the cooling plate  24 . As a result, it is possible to efficiently allow moisture contained in the outside air to condense on the cooling plate  24 .