Abstract:
A refrigerator unit is configured for a container in which it is possible to know the quantity of air that is ventilated. The refrigerator unit is equipped with a ventilation mechanism, an opening degree detecting mechanism, and a recording unit. The ventilation mechanism ventilates the air inside the container. The opening degree detecting mechanism acquires ventilation data related to the quantity of air ventilated by the ventilation mechanism. The recording unit records the ventilation data acquired by the opening degree detecting mechanism.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This nonprovisional application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2003-123493, filed in Japan on Apr. 28, 2003, the entire contents of which are hereby incorporated by reference. 
   TECHNICAL FIELD 
   The present invention is related to a refrigerator unit for a container. 
   BACKGROUND ART 
   For some time, refrigerator units for container have been used to cool the inside of containers used for freight transport and the like. Some of these refrigerator units for container are equipped with ventilation units for ventilating the interior of the container. For example, in the case of a container used for transporting fruits and vegetables, it is necessary to provide an appropriate degree of ventilation of the air inside the container in order to keep the fruits and vegetables fresh. A ventilation unit is therefore used to accomplish the ventilation of the interior of the container (see Japanese Laid-Open Patent Publication No. 9-280720). 
   Meanwhile, there is a need to know the quantity of air that is exchanged by the ventilation units used in container refrigeration units. In the example presented above, since the ventilation affects the freshness of the fruits and vegetables, knowing the quantity of air that has been ventilated is useful for maintaining the freshness of the fruits and vegetables. Also, if the quantity of ventilation is known, a transport company transporting fruits and vegetables can provide a fruit and vegetable owner with a guarantee that an appropriate degree of ventilation is being conducted. 
   However, it is difficult to know the quantity of air that is ventilated to and from conventional container refrigeration units like that just described. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is to provide a refrigerator unit for container for which it is possible to know the quantity of air that is ventilated. 
   A refrigerator unit for container in accordance with the first invention is equipped with a ventilation unit, an acquisition unit, and a recording unit. The ventilation unit ventilates the air inside the container. The acquisition unit acquires ventilation data related to the quantity of air ventilated by the ventilation unit. The recording unit records the ventilation data acquired by the acquisition unit. The ventilation data is not limited to data that indicates the quantity of ventilated air directly; it is also acceptable for the ventilation data to be data that indicates the quantity of ventilated air indirectly. 
   With this refrigerator unit for container, the interior of the container is ventilated and ventilation data related to the quantity of ventilated air is recorded. Consequently, it is possible to review the recorded ventilation data. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air. 
   A refrigerator unit for container in accordance with the second invention is a refrigerator unit for container according to the first invention, further equipped with a first output unit. The first output unit is configured to output the quantity of air ventilated by the ventilation unit based on the ventilation data recorded by the recording unit. 
   With this refrigerator unit for container, the quantity of air ventilated by the ventilation unit is outputted by the first output unit. Thus, with this refrigerator unit for container, it is possible to easily know the quantity of ventilated air. 
   A refrigerator unit for container in accordance with the third invention is a refrigerator unit for container according to the first invention, further equipped with a second output unit. The second output unit is configured to output the ventilation data recorded by the recording unit. 
   With this refrigerator unit for container, the ventilation data is outputted by the second output unit. Consequently, if the ventilation data is data that directly indicates the quantity of ventilated air, the quantity of ventilated air can be known directly. Meanwhile, if the ventilation data is data that indirectly indicates the quantity of ventilated air, the quantity of ventilated air can be known indirectly. Thus, with this refrigerator unit for container, it is possible to easily know the quantity of ventilated air. 
   A refrigerator unit for container in accordance with the fourth invention is a refrigerator unit for container according to any one of the first to third inventions, wherein the ventilation unit has a ventilation passage and an opening/closing member. The ventilation passage serves as a passage through which the ventilated air passes. The opening/closing member opens and closes the ventilation passage. The ventilation data includes opening degree data indicating the degree to which the opening/closing member has opened the ventilation passage. 
   With this refrigerator unit for container, the interior of the container is ventilated by opening and closing the ventilation passage with the opening/closing member. Consequently, the quantity of ventilated air is affected by the degree to which the opening/closing member opens the ventilation passage. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air based on the opening degree data. 
   A refrigerator unit for container in accordance with the fifth invention is a refrigerator unit for container according to the fourth invention, wherein the opening/closing member is configured to open and close the ventilation passage by being moved in a manual fashion. 
   With this refrigerator unit for container, the opening/closing member is configured to open and close the ventilation passage by being moved in a manual fashion. Conventionally, it is difficult to know the quantity of ventilated air when the opening degree of the ventilation passage is changed manually. For example, if the opening/closing member is manually moved more than once during a transport, at the end of the transport it is difficult to know the history of how the opening degree of the ventilation passage has changed. However, with this refrigerator unit for container, the opening degree data is recorded by the recording unit. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air. 
   A refrigerator unit for container in accordance with the sixth invention is a refrigerator unit for container according to the fourth or fifth inventions, wherein the acquisition unit has an opening degree detecting means. The opening degree detecting means detects the opening degree based on the amount of movement of the opening/closing member. 
   With this refrigerator unit for container, the opening degree detecting means detects the opening degree based on the amount of movement of the opening/closing member. As a result, the opening degree data can be acquired easily based on the movement amount of the opening/closing member. 
   A refrigerator unit for container in accordance with the seventh invention is a refrigerator unit for container according to the sixth invention, wherein the acquisition unit has a transmitting means configured to transmit the movement amount of the opening/closing member to the opening degree detecting means. 
   With this refrigerator unit for container, the transmitting means transmits the movement amount of the opening/closing member to the opening degree detecting means. As a result, the movement amount of the opening/closing member can be transmitted to the opening degree detecting means even if the opening/closing member and the opening degree detecting means are in separated positions. 
   A refrigerator unit for container in accordance with the eighth invention is a refrigerator unit for container according to the seventh invention, further equipped with a thermally insulated wall. The thermally insulated wall is made of a thermal insulation material and is arranged and configured to separate the interior and exterior of the container. The transmitting means is a member imbedded in the thermally insulated wall. 
   Refrigerator units for container are generally provided with a thermally insulated wall in order to maintain the temperature of the container interior. If the transmitting means is installed on the outside of the thermally insulated wall in a position facing the exterior of the container, it will affect the exterior appearance of the container. Conversely, if the transmitting means is installed on the inside of the thermally insulated wall in a position facing the interior of the container, it is possible that the ability of the transmitting means to transmit will be disturbed when the temperature of the container interior is extremely low. 
   However, with this refrigerator unit for container, the transmitting means is embedded in the thermally insulated wall. As a result, the transmitting means is prevented from affecting the external appearance of the container. Also, the transmitting means can transmit in a trouble-free manner without being affected by the temperature of the container interior. 
   A refrigerator unit for container in accordance with the ninth invention is a refrigerator unit for container according to the seventh or eighth inventions, further provided with a temperature detecting means and a correction unit. The temperature detecting means detects the ambient temperature surrounding the transmitting means. The correction unit corrects the opening/closing member movement amount transmitted by the transmitting means based on the ambient temperature. 
   With this refrigerator unit for container, the opening/closing member movement amount transmitted by the transmitting means is corrected based on the ambient temperature. As a result, even if the transmitting means elongates or shortens due to the temperature, the movement amount of the opening/closing means can be detected accurately. 
   A refrigerator unit for container in accordance with the tenth invention is a refrigerator unit for container according to any one of the fourth to ninth inventions, wherein the recording unit is configured to record ventilation data when the opening degree of the opening/closing member is changed. 
   With this refrigerator unit for container, ventilation data is recorded when the opening degree of the opening/closing member is changed. As a result, it is possible to know with good precision how the quantity of ventilated air has changed due to changes in the opening degree of the opening/closing member. 
   A refrigerator unit for container in accordance with the eleventh invention is a refrigerator unit for container according to any one of the first to tenth inventions, wherein the recording unit is configured to record ventilation data when the refrigerator unit for container starts running. 
   With this refrigerator unit for container, ventilation data is recorded when the refrigerator unit for container starts running. As a result, ventilation data can be obtained from the time when the refrigerator unit for container starts running. 
   A refrigerator unit for container in accordance with the twelfth invention is a refrigerator unit for container according to any one of the first to eleventh inventions, wherein the recording unit is configured to record ventilation data each time a specific amount of time elapses or at a specific time of day. 
   With this refrigerator unit for container, the ventilation data is recorded each time a specific amount of time elapses or at a specific time of day. As a result, it is possible to know how the quantity of ventilated air changes with respect to a specific repeated time interval or a specific time of day. 
   A refrigerator unit for container in accordance with the thirteenth invention is a refrigerator unit for container according to any one of the first to third inventions, wherein the ventilation unit has a ventilation passage and an air speed detecting means. The ventilation passage serves as a passage through which the ventilated air passes. The air speed detecting means detects the speed of the air passing through the ventilation passage. The ventilation data includes the air speed data detected by the air speed detecting means. 
   With this refrigerator unit for container, the air speed data detected by the air speed detecting means is recorded. The speed of the air passing through the ventilation passage indicates the quantity of ventilated air indirectly. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air because the air speed data is recorded. 
   A refrigerator unit for container in accordance with the fourteenth invention is a refrigerator unit for container according to any one of the first to third inventions, wherein the ventilation unit has a ventilation passage and a blower device. The ventilation passage serves as a passage through which the ventilated air passes. The blower device generates a flow of air that is ventilated through the ventilation passage. The ventilation data includes output data from the blower device. 
   With this refrigerator unit for container, the output data of the blower device is recorded. The output of the blower device indicates the quantity of ventilated air indirectly. For example, the larger the output of the blower device, the larger the quantity of ventilated air; the smaller the output of the blower device, the smaller the quantity of ventilated air. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air because the output data is recorded. 
   A refrigerator unit for container in accordance with the fifteenth invention is a refrigerator unit for container according to any one of the first to third inventions, wherein the ventilation unit has a ventilation passage and a pressure detecting means. The ventilation passage serves as a passage through which the ventilated air passes. The pressure detecting means detects the pressure difference between the inlet and outlet of the ventilation passage. The ventilation data includes the pressure difference data detected by the pressure detecting means. 
   With this refrigerator unit for container, the pressure difference data detected by the pressure detecting means is recorded. The pressure difference between the inlet and outlet of the ventilation passage indicates the quantity of ventilated air indirectly. For example, the larger the pressure difference between the inlet and outlet of the ventilation passage, the larger the quantity of ventilated air; the smaller the pressure difference between the inlet and outlet of the ventilation passage, the smaller the quantity of ventilated air. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air because the pressure difference data is recorded. 
   A refrigerator unit for container in accordance with the sixteenth invention is a refrigerator unit for container according to any one of the first to third inventions, wherein the ventilation data includes freight quantity data related to the quantity of freight loaded in the container. 
   With this refrigerator unit for container, freight quantity data related to the quantity of freight loaded in the container is recorded. The quantity of freight loaded in the container affects the pressure difference between the interior and exterior of the container. The pressure difference between the interior and exterior of the container affects the quantity of air that is ventilated. Thus, with this refrigerator unit for container, it is possible to know the quantity of ventilated air because the freight quantity data is recorded. 
   A refrigerator unit for container in accordance with the seventeenth invention is a refrigerator unit for container according to any one of the first to sixteenth inventions, wherein the ventilation data is data that indirectly indicates the quantity of air ventilated by the ventilation unit. Also, this refrigerator unit for container is further provided with a conversion unit configured to convert the ventilation data into a quantity of air. 
   With this refrigerator unit for container, the ventilation data is converted into a quantity of air by the conversion unit. Thus, even if the ventilation data is data that indirectly indicates the quantity of ventilated air, the quantity of ventilated air can be known directly by converting the ventilation data into the quantity of ventilated air. 
   A refrigerator unit for container in accordance with the eighteenth invention is a refrigerator unit for container according to the seventeenth invention, wherein the conversion unit has a plurality of different converting means adapted to different ventilation unit configurations. 
   The relationship between the ventilation data and the quantity of air often differs depending on the constituent features of the ventilation unit. Consequently, it is difficult to convert the ventilation data accurately when the same conversion formula is used irregardless of the constituent features of the ventilation unit. 
   With this refrigerator unit for container, however, the ventilation data is converted into a quantity of air using a plurality of different converting means adapted to different ventilation unit configurations. Thus, with this refrigerator unit for container, the ventilation data can be converted more accurately into the quantity of ventilated air. 

   
     BRIEF DESCRIPTIONS OF THE DRAWINGS 
       FIG. 1  is a perspective view showing the external appearance of the refrigerator unit for container  1 . 
       FIG. 2  is a side cross sectional view showing of the refrigerator unit for container  1 . 
       FIG. 3(   a ) shows the ventilation mechanism  4  in a completely closed state. 
       FIG. 3(   b ) shows the ventilation mechanism  4  in an opened state. 
       FIG. 3(   c ) shows the ventilation mechanism  4  in a completely opened state. 
       FIG. 4  is a schematic view of the opening degree detecting mechanism  5 . 
       FIG. 5  illustrates how the opening degree detecting mechanism  5  detects the opening degree. 
       FIG. 6  is a side cross sectional view in the vicinity of the thermally insulated wall  26 . 
       FIG. 7  is a control block diagram. 
       FIG. 8  is a graph plotting the first conversion formula F 1  and the second conversion formula F 2 . 
       FIG. 9  is a front view of the control panel  72 . 
       FIG. 10  illustrates an example of the output indicating the ventilation quantity and other information. 
       FIG. 11  is a flowchart indicating the procedure for logging and outputting the ventilation quantity. 
       FIG. 12(   a ) is a schematic view illustrating a case in which air speed data is detected. 
       FIG. 12(   b ) is a schematic view illustrating a case in which output data is detected. 
       FIG. 12(   c ) is a schematic view illustrating a case in which pressure difference data is detected. 
       FIG. 13(   a ) is a schematic view illustrating a case in which the opening degree of the ventilation passage  40  is detected using a photoelectric sensor  66 . 
       FIG. 13(   b ) is a schematic view illustrating a case in which the opening degree of the ventilation passage  40  is detected using a reed switch  67 . 
       FIG. 13(   c ) is a schematic view illustrating a case in which the movement of the opening/closing member  41  is transmitted by means of a gear. 
       FIG. 14(   a ) shows an opening/closing member  41  configured to open and close the ventilation passage  40  by rotating. 
       FIG. 14(   b ) is a schematic view illustrating a case in which the movement of the opening/closing member  41  is transmitted by means of a wire  51 . 
       FIG. 14(   c ) is a schematic view illustrating a case in which the movement of the opening/closing member  41  is transmitted by means of a gear. 
       FIG. 15  is a schematic view illustrating a case in which the ventilation passage  40  is provided in a position that is separated from the first chamber R 1  or the second chamber R 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Constituent Features of Refrigerator Unit for Container 
   A refrigerator unit for container  1  that employs an embodiment of the present invention is shown in  FIGS. 1 and 2 .  FIG. 1  is a perspective view of the external appearance of the refrigerator unit for container  1  and  FIG. 2  is a side cross sectional view of the refrigerator unit for container  1  when it is mounted to a container C. The refrigerator unit for container  1  is a device for maintaining a prescribed temperature in the interior IS of the freight container C and is mounted to an opening of the container C in such a manner as to separate the interior IS of the container C from the exterior OS of the same. The refrigerator unit for container  1  is provided with a frame  2 , refrigerant circuit component parts  3 , a ventilation mechanism  4  (ventilation unit), an opening degree sensing mechanism  5  (acquisition unit), various sensors  6  (see  FIG. 7 ), and a control unit  7 . 
   &lt;Frame&gt; 
   The frame  2  has a generally sheet-like shape and is mounted in such a fashion as to block one side of the container C. As shown in  FIG. 2 , the frame  2  is provided with an exterior storage space SP 1  and an interior storage space SP 2 . 
   The exterior storage space SP 1  has a recessed shape and is formed in a lower portion of a front face  21  on the side of the frame  2  that faces the exterior OS of the container C. The exterior storage space SP 1  is isolated from the interior IS of the container C and communicates with the exterior OS of the container C. The upper portion of the front face  21  has a flat shape that is generally parallel to the vertical direction. 
   The interior storage space SP 2  is arranged between the front face  21  and a rear panel  22 . The rear panel  22  faces the interior IS of the container C and is separated from the front face  21  by a prescribed distance. The interior storage space SP 2  spans from the rear (rear panel side) of the external storage space SP 1  to space above the exterior storage space SP 1  and communicates with the interior IS of the container C through air vents  23 ,  24  provided near the top and bottom ends of the rear panel  22 . A plate-shaped fan guide  25  is provided in a generally horizontal state in the interior storage space SP 2 . The an evaporator fan  36  (described later) is mounted to the fan guide  25 . The interior storage space SP 2  is divided by the fan guide  25  and evaporator fan  36  into a first chamber R 1  located above the fan guide  25  and a second chamber R 2  located below the fan guide  25 . 
   A thermally insulated wall  26  is provided on the rear side of an upper portion of the front face  21  between the interior storage space SP 2  and the exterior OS and on the rear side of a lower portion of the front face  21  between the interior storage space SP 2  and the exterior storage space SP 1 . The thermally insulating wall  26  is made of a thermal insulation material and is arranged and configured to separate the interior IS and exterior OS of the container C. The thermally insulated wall  26  serves to suppress the movement of heat between the interior IS and exterior OS of the container C. 
   &lt;Refrigerant Circuit Component Parts&gt; 
   The refrigerant circuit component parts  3  include such parts as a condenser  30 , a compressor  31 , an expansion valve  32  (see  FIG. 7 ), and an evaporator  33  and these parts constitute a refrigerant circuit. 
   The condenser  30 , the compressor  31 , and the expansion valve  32  are housed in the external storage space SP 1 . The external storage space SP 1  also houses a condenser fan  34  and a condenser fan motor  35 . The condenser fan  34  is rotated by the condenser fan motor  35  and serves to produce a flow of air that is drawn into the exterior storage space SP 1  from the exterior OS, passes through the condenser  30 , and is discharged to the exterior OS (see unshaded arrow A 1 ). 
   The evaporator  33  is housed in the second chamber R 2  of the interior storage space SP 2  on the rear side of the upper portion of the front face  21 . The internal storage space SP 2  also houses an evaporator fan  36  and an evaporator fan motor  37 . The evaporator fan  36  and evaporator fan motor  37  are arranged above the evaporator  33 . The evaporator fan  36  is provided in the opening of the fan guide  25  and is positioned between the first chamber R 1  and the second chamber R 2 . The first chamber R 1  is positioned on the inlet side of the evaporator fan  36  and the second chamber R 2  is positioned on the outlet side of the evaporator fan  36 . The evaporator fan  36  is rotated by the evaporator fan motor  37  and produces an interior air flow. The interior air flow flows from the interior IS of the container C through the air vent  23  at the upper end of the rear panel  22  and into the first chamber R 1  of the interior storage space SP 2  (see unshaded arrow A 2 ). The interior air flow then flows from the first chamber R 1  through the opening of the fan guide  25  and into the second chamber R 2 , where it passes through the evaporator  33  arranged in the second chamber R 2 . Then, the interior air flow flows through the vent  24  at the lower end of the rear panel  22  to the interior IS (see unshaded arrow A 3 ). 
   &lt;Ventilation Mechanism&gt; 
   The ventilation mechanism  4  serves to ventilate the interior IS of the container C and is provided with a ventilation passage  40  and an opening/closing member  41 . 
   The ventilation passage  40  is a passage through which the ventilated air passes and has an intake passage  42  and an exhaust passage  43 . The intake passage  42  and exhaust passage  43  are provided so as to be aligned above and below each other in an upper portion of the front surface  21 ; the inlet passage  42  is positioned above the exhaust passage  43 . The exhaust passage  42  is the passage through which air is drawn into the first chamber R 1  from the exterior OS of the container C and is arranged and configured to communicate from an intake port  44  to the first chamber R 1  through the thermally insulated wall  26 . The exhaust passage  43  is the passage through which air is discharged to the exterior OS of the container C from the second chamber R 2  and is arranged and configured to communicate to an exhaust port  45  and the exterior OS through the thermally insulated wall  26 . The intake port  44  and the exhaust port  45  are provided in an upper portion of the front face  21  and arranged so as to face the exterior OS with a prescribed vertical spacing there-between. As shown in  FIG. 3 , the intake port  44  and the exhaust port  45  have the shapes of trapezoids arranged such that the upper and lower bases are parallel to the vertical direction. The upper edges of the intake port  44  and the exhaust port  45  are horizontal and the bottom edges are slanted. 
   The opening/closing member  41  serves to open and close the ventilation passage  40 . The opening/closing member  41  is provided such that it slides freely up and down over the front face  21 . The opening/closing member  41  serves to adjust the quantity of ventilated air by adjusting the opening degree of the intake port  44  and the exhaust port  45  in accordance with its slide position. As shown in  FIG. 3(   a ), the opening/closing member  41  has the shape of a rectangle that is long in the vertical direction in a frontal view and is provided with a square opening  46  in the center thereof. 
   When the ventilation passage  40  is closed, the opening  46  of the opening/closing member  41  is positioned between the intake port  44  and the exhaust port  45  such that the intake port  44  and the exhaust port  45  are closed by the opening/closing member  41 . As shown in  FIG. 3(   b ), the opening cross sectional areas of the intake port  44  and exhaust port  45  increase in accordance with the amount of movement of the opening/closing member  41  when the opening/closing member  41  is slid in the vertical direction. When the opening/closing member is moved in this way and the exhaust passage  40  is opened, pressure differences causes the interior IS of the container C to be ventilated. The pressure differences mentioned here are the pressure difference between the interior IS and the interior storage space SP 2  and the pressure difference between the exterior OS and the interior storage space SP 2 . Since the first chamber R 1  is positioned on the inlet side of the evaporator fan  36 , its pressure is lower than the pressures of both the interior IS and the exterior OS. Consequently, air is drawn from the interior IS to the first chamber R 1  through the air vent  23 . Likewise, air is drawn from the exterior OS to the first chamber R 1  through the intake port  44  and intake passage  42 . The air drawn into the first chamber R 1  is pulled through the opening of the fan guide  25  by the evaporator fan  36  and delivered to the second chamber R 2 . Since the second chamber R 2  is positioned on the outlet side of the evaporator fan  36 , its pressure is higher than the pressures of both the interior IS and the exterior OS. Consequently, a portion of the air delivered to the second chamber R 2  is discharged to the exterior OS through the exhaust passage  43  and the exhaust port  45 . Meanwhile, the remainder of the air delivered to the second chamber R 2  is sent to the interior IS through the evaporator  33  and the air vent  24 . In this way, with this refrigerator unit for container  1 , the pressure difference generated by the evaporator fan  36  is utilized to ventilate the container C. By moving the opening/closing member  41 , the opening degree of the ventilation passage  40  is adjusted and thus the ventilation quantity is adjusted. As shown in  FIG. 3(   c ), the ventilation passage  40  is completely open when the positions of the opening  46  of the opening/closing member  41  and the intake port  44  are aligned. 
   When the opening/closing member  41  is slid in the opposite direction as just described, the opening cross sectional areas of the intake port  44  and exhaust port  45  decrease in accordance with the amount of movement of the opening/closing member  41 . The ventilation passage  40  is fully closed when the opening  46  of the opening/closing member  41  is positioned between the intake port  44  and the exhaust port  45  (see  FIG. 3(   a )). A graduated scale is provided in near the opening/closing member  41  and the opening/closing member  41  is moved manually using this scale as an indicator of the ventilation quantity. 
   &lt;Opening Degree Detecting Mechanism&gt; 
   The opening degree detecting mechanism  5  is configured to acquire opening degree data (ventilation data) indicating the opening degree of the ventilation passage  40 . The opening degree data indicates the quantity of air ventilated by the ventilating mechanism  4  (hereinafter called “ventilation quantity”) indirectly. As shown in  FIG. 4 , the opening degree detecting mechanism  5  is provided with an opening degree detecting device  50  (opening degree detecting means) and a wire  51  (transmitting means) configured and arranged to transmit the amount of movement of the opening/closing member  41  to the opening degree detecting device  50 . 
   The opening degree detecting device  50  is arranged in the exterior storage space SP 1  and serves to detect the opening degree of the ventilation passage  40  based on the movement amount of the opening/closing member  41 . The opening degree detecting device  50  has a wire winding drum  52  and a position meter  53 . The wire winding drum  52  has a circular shape for winding the wire  51  and is configured to rotate in accordance with the movement of the wire  51  (see unshaded arrow A 6 ). The position meter  53  serves to detect the rotational angle of the wire winding drum  52  and send the detected rotational angle to a controller  7 . In short, the position meter  53  can detect the opening degree of the ventilation passage  40  by detecting the movement amount and position of the opening/closing member  41  based on the rotational angle of the wire winding drum  52 . 
   The wire  51  is a metal wire member configured and arranged to transmit the movement amount of the opening/closing member  41  to the opening degree detecting device  50 . The wire  51  is arranged to span from the upper portion of the front face  21  where the opening/closing member  41  is provided to the exterior storage space SP 1  where the opening degree detecting device  50  is arranged and, as shown in  FIG. 5 , the wire  51  links the opening/closing member  41  and the wire winding drum  52  together.  FIG. 5  illustrates the linkage of the opening/closing member  41  and the wire winding drum  52  in a simplified schematic manner. As shown in  FIG. 6 , the wire  51  is inserted through a lead-through pipe  54  embedded in the thermally insulated wall  26 . The lead-through pipe  54  passes from the upper portion of the front face  21  where the opening/closing member  41  is provided, through the interior of the thermally insulated wall  26 , and down into the exterior storage space SP 1  and serves to guide the wire  51  from the upper portion of the front face  21  to the external storage space SP 1 . The wire  51  moves through the lead-through pipe  54  (see unshaded arrow A 5 ) in accordance with the movement of the opening/closing member  41  (see unshaded arrow A 4 ) and thereby transmits the movement of the opening/closing member  41  to the opening degree detecting device  50 . 
   Thus, with this opening degree detecting mechanism  5 , the opening/closing member  41  and the opening degree detecting device  50  can be arranged in separated positions because the movement amount of the opening/closing member  41  is transmitted to the opening degree detecting device  50  by the wire  51 . 
   &lt;Sensors&gt; 
   The sensors  6  include an exterior temperature sensor  61  (temperature detecting means) for detecting the temperature of the exterior OS of the container C and an interior temperature sensor  62  for detecting the temperature of the interior IS of the container C (see  FIG. 7 ). The exterior temperature, interior temperature, and other information detected by the sensors are sent to the controller  7 . 
   &lt;Controller&gt; 
   The controller  7  is a device for controlling the refrigerator unit for container  1  and is arranged in the external storage space SP 1 . As shown in  FIG. 7 , the controller  7  has a control unit  70  comprising a CPU or the like, a memory  71 , a control panel  72  for displaying information and making entries to control, an output unit  78 , etc. 
   The control unit  70  is connected to the compressor  31 , the condenser fan motor  35 , the expansion valve  32 , the evaporator fan motor  37 , and the sensors  6  and serves to control the operation of the refrigerator unit for container  1 . The control unit  70  is also connected to the position meter  53  of the opening degree detecting device  50  and is configured to log (record) the ventilation quantity in the memory  71  based on the information detected by the opening degree detecting device  50 . The control unit  70  has a conversion unit  73 , a correction unit  74 , and a recording unit  75 . 
   The conversion unit  73  converts the opening degree data, which indicates the ventilation quantity indirectly, into the ventilation quantity. More specifically, the conversion unit  73  is configured to convert the movement amount of the opening/closing member  41  detected by the opening degree detecting device  50  into a quantity of ventilated air. Since the opening cross sectional areas of the intake port  44  and exhaust port  45  are adjusted when the opening/closing member  41  moves, the movement amount of the opening/closing member  41  corresponds to the quantity of ventilated air. Thus, the quantity of ventilated air can be calculated using a conversion formula that indicates the correspondence between the movement amount of the opening/closing member  41  and the quantity of ventilated air. The conversion unit  73  is provided with a first conversion formula F 1  (conversion means) and a second conversion formula F 2  as shown in  FIG. 8  and is configured to use either conversion formula, whichever is selected. The first conversion formula F 1  indicates the correspondence between the movement amount of the opening/closing member  41  and the quantity of ventilated air in a case where a protective screen is not mounted to the intake port  44  and exhaust port  45 . The second conversion formula F 2  indicates the correspondence between the movement amount of the opening/closing member  41  and the quantity of ventilated air in a case where a protective screen is mounted to the intake port  44  and exhaust port  45  and is different from the first conversion formula F 1 . The protective screen serves to prevent contaminants from entering the interior IS of the container C from the exterior OS and is mounted to the intake port  44  and exhaust port  45 . Since the pressure difference between the first chamber R 1  and the exterior OS is different in a case where a protective screen is mounted to the intake port  44  and exhaust port  45  than in a case where a protective screen is not provided, the first conversion formula F 1  and the second conversion formula F 2  are different. Thus, a more accurate conversion can be accomplished by using the conversion formulas F 1 , F 2  selectively depending on the constituent features of the ventilation mechanism  4 . 
   The correction unit  74  corrects the movement amount of the opening/closing member  41  transmitted by the wire  51  based on the exterior temperature. More specifically, since the wire  51  expands and contracts as the temperature changes, error occurs in the movement amount of the opening/closing member  41  depending on the change in the temperature. The correction unit  74  is configured to compensate for the error that results from changes in the exterior temperature. The correction unit  74  corrects the detected movement amount using, for example, the formula shown below.
 
1 c =1 t ×{1+α( t−t   0 )}
 
   In the formula, 1 c  is the corrected movement amount, 1 t  is the actual measured value of the movement amount, α is the coefficient of linear thermal expansion of the wire  51 , t is the exterior temperature at the time when the movement amount is detected, and t 0  is the exterior temperature when setting the zero-point. 
   Since the error resulting from expansion and contraction of the wire  51  is corrected in this way, the ventilation quantity can be calculated more accurately. 
   Although in this embodiment the correction is performed using the exterior temperature as the ambient temperature of the wire  51 , it is also acceptable to detect the temperature near the wire  51  and use the detected temperature for the correction. 
   In addition to logging the history of the ventilation quantity in the memory  71 , the recording unit  75  displays the ventilation quantity on a display panel  76  (first output unit and second output unit) of the control panel  72  (see  FIG. 9 ). The recording unit  75  records the history of the ventilation quantity, which comprises the ventilation quantities obtained by converting the opening degree of the ventilation passage  40  and the dates (year/month/day) and times of day when the ventilation quantities were recorded, in the memory  71 . The recording unit  75  logs the ventilation quantity history at the following three timings. The first timing is when the refrigerator unit for container  1  starts running. That is, the recording unit  75  logs the ventilation quantity and other data when the compressor  31 , evaporator fan motor  37 , and condenser fan motor  35  are driven and the refrigerator unit for container  1  starts cooling the interior IS of the container C. The second timing is each time a specific amount of time elapses or at a specific time of day. For example, the recording unit  75  might log the ventilation quantity and other data once per day at a specific time (e.g., 00:00 AM). The third timing is when the opening degree of the ventilation passage  40  is changed. That is, the recording unit  75  logs the ventilation quantity and other data when the opening/closing member  41  is moved and the opening degree of the ventilation passage  40  is changed. By logging the ventilation quantity and other data at these three timings, the ventilation quantity can be logged in a more detailed fashion. Thus, the ventilation quantity can be known in more detail. Additionally, the value of the ventilation quantity is logged according to a prescribed incremental value. For example, in consideration of the conversion error between the opening degree and the ventilation quantity, the ventilation quantity might be logged in increments of 5 m 3 /h. 
   The control panel  72  is arranged in the external storage space SP 1  of the front face  21  and faces the exterior OS. As shown in  FIG. 9 , the control panel  72  is provided with a display panel  76  and input keys  77 . The display panel  76  displays such information as the interior temperature of the container C and the ventilation quantity obtained by converting the opening degree data. The input keys  77  are used to turn the refrigerator unit for container  1  on and off and to enter operation details. 
   The ventilation quantity is not only displayed on the display panel  76  but also outputted by the output unit  78  (first output unit and second output unit). The output unit  78  outputs the logged history of the ventilation quantity. The output unit  78  is, for example, a printer serving to print the ventilation quantities, dates (year/month/day), and times that have been logged, a write device configured to write the ventilation quantities and other data to a recording medium as electronic data, or an output port for transmitting the ventilation quantities and other data to another information terminal through a communication cable or wireless connection as electronic data. An example of the ventilation quantity history list outputted by the output unit  78  is shown in  FIG. 10 . In this history list, the ventilation quantity D 1  is a ventilation quantity logged when the opening degree of the ventilation passage  40  is changed. The ventilation quantity D 2  is a ventilation quantity logged at a specific time of day. The ventilation quantity D 3  is a ventilation quantity logged when the refrigerator unit for container  1  started operating. The ventilation quantities D 1 , D 2 , D 3  are outputted together with the temperatures T 1  and the date (year/month/day) and time T 2  when the ventilation quantities D 1 , D 2 , D 3 , and the interior temperature T were detected. The temperatures T 1  are the temperature setting, the interior temperature of the container C detected during transport, etc. The temperatures T 1  and the ventilation quantities D 1 , D 2 , D 3  are detected and recorded at a plurality of times T 2  during transport. 
   &lt;Logging and Output of Ventilation Quantities&gt; 
   The procedure for logging the ventilation quantity will now be described based on the flowchart shown in  FIG. 11 . 
   In step S 1 , the ventilation passage  40  is closed or opened. In this embodiment, the opening degree of the ventilation passage  40  is changed manually by sliding the opening/closing member  41 . When the opening/closing member  41  is moved, the wire  51  is either pulled or pushed in accordance with the movement of the opening/closing member  41 . The movement of the wire  51  is transmitted to the wire winding drum  52  and the wire winding drum  52  rotates. 
   In step S 2 , the opening degree is detected. In this embodiment, the position meter  53  detects the rotational angle of the wire winding drum  52 . The opening degree of the ventilation passage  40  is outputted from the opening degree detecting device  50 . That is, the opening degree of the ventilation passage  40  is outputted in the form of the rotational angle of the wire winding drum  52 . The outputted opening degree is sent to the control unit  70  of the controller  7 . 
   In step S 3 , a conversion calculation is executed to obtain the ventilation quantity. In this embodiment, the opening degree of the opening/closing member  41  is converted to a ventilation quantity using either the first conversion formula F 1  or the second conversion formula F 2 . 
   In step S 4 , the ventilation quantity and other data is logged and displayed. In this embodiment, the conversion-calculated ventilation quantity and the date (year/month/day) and time it was logged are recorded in the memory  71  and the ventilation quantity is displayed on the display panel  76 . The logging and display of the ventilation quantity and other data are performed at the aforementioned three timings. The output unit  78  outputs the history of the ventilation quantity and other data. 
   &lt;Characteristic Features&gt; 
   &lt;1&gt; 
   With this refrigerator unit for container  1 , the interior IS of the container C is ventilated and the ventilation quantity is logged. As a result, the fact that the opening/closing member  41  was moved and ventilation was conducted during transport of a container C can be confirmed afterwards by checking the ventilation quantity history. 
   In particular, it is difficult to check the history of the opening degree of the opening/closing member  41  and the ventilation quantity when the opening/closing member  41  is moved a plurality of times. However, with this refrigerator unit for container  1 , the history of the ventilation quantity can be known easily by outputting the logged ventilation quantities. 
   For example, in the case of a container C used to transport fruit, it is necessary to exhaust the ethylene gas generated by the fruit and draw in fresh outside air. Therefore, it is important to manage the ventilation quantity in order to maintain the freshness of the fruit. With this refrigerator unit for container  1 , by logging the ventilation quantity, a transport company transporting the container C can provide the fruit owner with a guarantee that a certain amount of ventilation is conducted. 
   &lt;2&gt; 
   With this refrigerator unit for container  1 , the opening degree of the ventilation passage  40  is detected based on the amount of movement of the opening/closing member  41  and the ventilation quantity is calculated based on the opening degree. As a result, ventilation quantity can be obtained with a system having a simple configuration.
         &lt;Other Embodiments&gt;       

   &lt;1&gt; 
   In the embodiment described above, the ventilation quantity is found using the movement amount of the opening/closing member  41  and a conversion formula. It is also acceptable to find the ventilation quantity based on the speed of the ventilated air and the opening cross sectional area. For example, as shown in  FIG. 12(   a ), an air speed sensor  63  (air speed detecting means) can be provided in the ventilation passage  40 . In such a refrigerator unit for container as this, an air speed sensor  63  that detects the speed of the air passing through the exhaust passage  43  is provided in the exhaust passage  43 . The control unit  70  logs data (ventilation data) that includes the air speed data detected by the air speed sensor  63  and the opening cross sectional area. The control unit  70  converts the air speed data into a ventilation quantity by finding the product of the detected air speed and the opening cross sectional area of the exhaust port  45  and logs the resulting ventilation quantity. In view of improving the detection accuracy, it is preferred that the air speed sensor  63  be mounted on the side where the opening/closing member  41  begins to open. 
   &lt;2&gt; 
   Although in the embodiment described above, the ventilation quantity is found using the movement amount of the opening/closing member  41  and a conversion formula, when the refrigerator unit for container  1  is provided with a blower device  47  for ventilation as shown in  FIG. 12(   b ), it is also acceptable to detect the output of the blower device  47  and log the detected output data (ventilation data). It is also acceptable to convert the output data into a ventilation quantity and log the ventilation quantity. The blower device  47  conducts ventilation by creating a flow of air that flows from the second chamber R 2  to the exterior OS and a flow of air that flows from the exterior OS to the first chamber R 1 . Since the ventilation quantity is affected by the output of the blower device  47 , the controller  70  can find the ventilation quantity based on the output of the blower device. 
   &lt;3&gt; 
   In the embodiment described above, the ventilation quantity is found using the movement amount of the opening/closing member  41  and a conversion formula. It is also acceptable to find the ventilation quantity by detecting the pressure difference between the exterior OS and the interior IS. For example, as shown in  FIG. 12(   c ), there may be a refrigerator unit for container  1  provided with an exterior pressure sensor  64  (pressure detecting means) that detects the pressure of the exterior OS and an interior pressure sensor  65  (pressure detecting means) that detects the pressure of the first chamber R 1  or the second chamber R 2 . In such a refrigerator unit for container  1  as this, pressure difference data (ventilation data) indicating the difference between the exterior pressure detected by the exterior pressure sensor  64  and the interior pressure detected by the interior pressure sensor  65  are logged. The output data can then be converted into a ventilation quantity and logged. 
   The ventilation of the air in the interior IS of the container C takes place due to the pressure difference between the exterior OS and the interior IS. In other words, the existence of a pressure difference between the exterior OS and the interior IS causes a flow of air that flows from the exterior OS to the interior IS or a flow of air that flows from the interior IS to the exterior OS to be generated. As a result, ventilation occurs. Thus, the ventilation quantity can be found by detecting the pressure difference between the exterior OS and the interior IS. 
   It is also acceptable to log freight quantity data related to the quantity of freight in the interior IS of the container C and find the ventilation quantity using the freight quantity data. The quantity of freight in the interior IS of the container C affects the pressure difference between the exterior OS and the interior IS. In other words, the pressure inside the container C is different when the quantity of freight in the interior IS of the container C is large than when the quantity of freight is small. Thus, the ventilation quantity can be found by taking the freight quantity data into consideration. 
   &lt;4&gt; 
   Although in the embodiment described above, the opening degree of the ventilation passage  40  is detected by using a wire  51  to transmit the movement of the opening/closing member  41  to an opening degree detecting device  50 , it is also acceptable to detect the opening degree of the ventilation passage  40  with a photoelectric sensor  66  (opening degree detecting means) as shown in  FIG. 13(   a ). The photoelectric sensor  66  is arranged to face the opening/closing member  41  in the direction in which the opening/closing member  41  moves so that it can detect the distance between itself and the opening/closing member  41 . With this arrangement, the movement amount of the opening/closing member  41  and thus the opening degree of the ventilation passage  40  imposed by the opening/closing member  41  can be detected. It is also acceptable to detect the amount of movement of the opening/closing member  41  using radio waves instead of light. 
   &lt;5&gt; 
   Although in the embodiment described above, the opening degree of the ventilation passage  40  is detected by using a wire  51  to transmit the movement of the opening/closing member  41  to an opening degree detecting device  50 , it is also acceptable to detect the opening degree of the ventilation passage  40  with a plurality of reed switches  67  (opening degree detecting means) as shown in  FIG. 13(   b ). The reed switches  67  are arranged parallel to the slide direction of the opening/closing member  41  and are configured to enter an on state when exposed to a magnetic force. A magnet  68  is provided on the opening/closing member  41  and the magnet  68  moves over the reed switches  67  when the opening/closing member  41  moves. Thus, the movement amount and position of the opening/closing member  41  can be detected based on the on/off status of the reed switches  67 . 
   It is also acceptable to detect the opening degree of the ventilation passage  40  using a plurality of limit switches. In such a case, the limit switches are arranged parallel to the slide direction of the opening/closing member  41  and are configured to enter an on state when subjected to mechanical contact. A lever configured and arranged to contact the limit switches is provided on the opening/closing member  41  so that when the opening/closing member  41  moves, the limit switches in positions through which the opening/closing member  41  has passed are turned on. Thus, the movement amount of the opening/closing member  41  can be detected based on the on/off status of the limit switches. 
   &lt;6&gt; 
   Although in the embodiment described above, the movement of the opening/closing member  41  is transmitted to the opening detecting device  50  by means of a wire  51 , it is also acceptable to transmit the movement of the opening/closing member  41  to the opening degree detecting device  50  with a gear  55  (transmitting means) as shown in  FIG. 13(   c ). The gear  55  has a circular shape and is arranged to the side of the opening/closing member  41 . A linear gear  56  is provided on a side edge of the opening/closing member  41  and the linear gear  56  of the opening/closing member  41  meshes with the gear  55 . A position meter  53  is mounted to the rotational center of the gear  55  and serves to detect the rotational angle of the gear  55 . Thus, when the opening/closing member  41  moves up and down, the gear  55  rotates (see solid arrow A 6 ) and the position meter  53  detects the movement amount of the opening/closing member  41  in the form of the rotational angle of the gear  55 . As a result, the opening degree of the ventilation passage  40  can be detected. 
   &lt;7&gt; 
   Although in the embodiment described above, the ventilation passage  40  is opened and closed by sliding the opening/closing member  41  linearly up and down, it is also acceptable to open and close the ventilation passage  40  by rotating an opening/closing member  48  as shown in  FIG. 14(   a ). The opening/closing member  48  has a circular shape and is mounted to the upper portion of the front face  21  such that its center is positioned between the intake port  44  and the exhaust port  45 . Two openings  481 ,  482  corresponding to the intake port  44  and the exhaust port  45  are provided in the opening/closing member  48 . When the opening/closing member  48  rotates (see the solid arrow A 7 ), the two openings  481 ,  482  overlap the intake port  44  and exhaust port  45  and thereby open the intake port  44  and exhaust port  45 . When the portions of the opening/closing member  48  other than the openings  481 ,  482  overlap the intake port  44  and exhaust port  45 , the intake port  44  and exhaust port  45  are closed. In  FIG. 14(   a ), the two openings  481 ,  482  are positioned such that the ports are completely closed. When an opening/closing member  48  like that shown in  FIG. 14(   a ) is rotated 90 degrees from a position where the portions of the opening/closing member  48  other than the openings  481 ,  482  are aligned with the intake port  44  and exhaust port  45 , the ventilation passage  40  is completely closed. When the opening/closing member  48  is rotated 90 degrees further or 90 degrees in the opposite direction to a position where the two openings  481 ,  482  are aligned with the intake port  44  and exhaust port  45 , the ventilation passage  40  is completely open. A position meter  53  is mounted to the center of the gear  48  and serves to detect the rotational angle of the opening/closing member  48  as the movement amount of the opening/closing member  48 , i.e., as the opening degree of the ventilation passage  40 . 
   It is also acceptable to provide the position meter  53  in a position separated from the position meter  53  instead of at the center of the opening/closing member  48 . For example, as shown in  FIG. 14(   b ), an opening degree detecting device  50  comprising a wire winding drum  52  and a position meter  53  arranged at the center of the wire winding drum  52  can be arranged in a position separated from the opening/closing member  48  and a wire  51  can be used to transmit the rotation of the opening/closing member  48  to the wire winding drum  52 . It is also acceptable to provide a circular gear  57 ,  58  (transmitting means) at the center of each of the opening/closing member  48  and the position meter  53  and to provide another circular gear  59  (transmitting means) that is positioned between and meshes with the gears  57 ,  58 , as shown in  FIG. 14(   c ). With this arrangement, too, the rotation of the opening/closing member  48  is transmitted to the position meter  53  by the gears  55 ,  57 ,  58 ,  59  and the opening degree of the ventilation passage  40  can be detected. When a wire winding drum  52  or gears  57 ,  58 ,  59  are used as described above, the resolution with which the movement amount of the opening/closing member  48  is detected can be changed easily by changing the diameter of the wire winding drum  52  or the gear ratio of the gears  57 ,  58 ,  59 . 
   &lt;8&gt; 
   In the embodiment described above, the intake port  44  and the exhaust port  45  are provided closely adjacent to the first chamber R 1  and the second chamber R 2 , respectively. However, due to various circumstances, there are cases in which the intake port  44  and the exhaust port  45  are provided in positions separated from the first chamber R 1  or second chamber R 2 . In such cases, a duct joining the intake port  44  and first chamber R 1  and a duct joining the exhaust port  45  and second chamber R 2  can be provided. For example, consider a case in which the exhaust port  45  and intake port  44  are provided in the lower portion of the front face  21  such that the intake port  44  is separated from the first chamber R 1 , as shown in  FIG. 15 . In such a case as this, it is acceptable to provide a duct  49  that runs from the first chamber R 1 , passes through the second chamber R 2 , penetrates the thermally insulated wall  26  and the front face  21 , and connects to the intake port  44 . In this way, even though the intake port  44  is in a position separated from the first chamber R 1 , air drawn into the intake port  44  from the exterior OS can be delivered to the first chamber R 1  by the duct  49  (see solid arrow A 6 ). 
   In the case of marine freight containers C, there are times when the refrigerator unit for container runs at terminals and the like in order to keep the freight cool after disembarkation. In such cases, a generator G is often installed on the upper portion of the front face  21  as shown in  FIG. 15  because a power supply is not available. Consequently, the intake port  44  and exhaust port  45  cannot be provided in the upper portion of the front face  21  and must be provided in the lower portion of the front face  21 . Therefore, particularly in cases where ventilation is accomplished by utilizing pressure differences, it is effective to provide a duct(s)  49  as just described in order to ventilate the container. 
   &lt;9&gt; 
   Although in the embodiment described above, ventilation quantities calculated based on the opening degree data are outputted to the display panel  76  of the control panel  72  and the output unit  78 , it is also acceptable to output such ventilation data as opening degree data. 
   &lt;10&gt; 
   Although in the embodiments described above, such data as opening degree data, air speed data, output data, pressure difference data, and freight quantity data that indicate the ventilation quantity indirectly are detected and logged, it is also acceptable to provide a ventilation quantity sensor that detects the ventilation quantity directly and log the detected ventilation quantity. 
   &lt;11&gt; 
   Although in the embodiments described above, the ventilation quantity is logged in a controller  7  arranged in the exterior storage space SP 1 , it is also acceptable to log the ventilation quantity in an external computer terminal, such as a desktop computer or notebook computer. 
   APPLICABILITY TO INDUSTRY 
   By using a refrigerator unit for container in accordance with the present invention, the quantity of air ventilated in the interior of a container can be known because recorded ventilation data related to the quantity of ventilated air can be reviewed afterwards.