Patent Publication Number: US-RE48198-E

Title: Loading space variable refrigeration system of refrigerator car

Description:
TECHNICAL FIELD 
     The present invention relates to a loading space variable refrigeration system of a refrigerator vehicle, and more particularly, to a loading space variable refrigeration system of a refrigerator vehicle, which can vary a loading space in a refrigeration trailer of a refrigerator vehicle according to volume of loads, thereby reducing fuel and oil costs for cool-air supply, and rapidly varying the loading space through simple operator manipulation. 
     BACKGROUND ART 
     In general, refrigerator vehicles are used to carry loads such as food products that may lose freshness thereof depending upon temperature. 
     Refrigerator vehicles for carrying various types of frozen or low-temperature foods/goods that cannot be stored or carried at room temperature may be classified into small straight trucks and medium and large semi-trailers according to a type and load capacity thereof. It should be understood that, terms, such as refrigerator vehicles, refrigeration trailers and refrigerators, as used herein, do not mean only refrigerating functions excluding freezing functions, and comprehensively include terms such as freezer vehicles, freezing trailers, and freezers. 
     As shown in  FIG. 1 , a refrigerator vehicle is provided at a loading station thereof with a refrigeration trailer  20  having an enclosure shape, and a refrigerator  21  is provided at a head side of the refrigerator vehicle or at one upper side of the refrigeration trailer  20 . The inner space of the refrigeration trailer  20  is maintained at a low temperature by an evaporator of the refrigerator  21 . The refrigerator  21  is usually an engine driven refrigerator that is driven by a main engine or sub-engine of the refrigerator vehicle. 
     In a refrigeration cycle of the refrigerator  21 , a refrigerant circulates via circulation pipes in order of compressor, condenser, expander, and evaporator. 
     Operation of the refrigerator  21  is as follows: the compressor is driven by power of a sub-engine provided at the refrigeration trailer  20 , a high-temperature, low-pressure refrigerant is changed into a medium-temperature, high-pressure refrigerant in the condenser as the compressor is driven, the refrigerant supplied from the condenser passes through the expansion valve and flows into the evaporator, the liquid refrigerant absorbs ambient heat while being instantaneously gasified, and cool air is created around the evaporator and discharged into the refrigeration trailer  20  by a separate exhaust fan. 
     Through constant repetition of the refrigeration cycle, the inner space of the refrigeration trailer  20  is maintained at a preset low temperature, which makes it possible to stably carry all foods and beverages required to be refrigerated or frozen and low-temperature goods under an optimal temperature condition. 
       FIG. 2  shows an interior of the refrigeration trailer in the related art. 
     Cool air supplied by the refrigerator  21  is fed into all spaces in the refrigeration trailer  20  through a duct  30  disposed at an upper portion of the refrigeration trailer  20 . The duct  30  is open at some portions of left and right sides thereof and at a distal end thereof. As shown in  FIG. 2 , some cool air is supplied to loads (L) through the left and right openings, and the rest is supplied through the distal opening to the inner space of the refrigeration trailer  20  and circulates therein. 
     However, the refrigeration system of the refrigeration trailer  20  supplies cool air into the refrigeration trailer  20  irrespective of quantity and volume of the loads (L) in order to maintain the entire inner space of the refrigeration trailer  20  at a preset temperature, which causes unnecessary energy (heat or fuel) consumption even when the loads (L) are small in quantity and volume. 
     Although refrigerator vehicle have an intake weight determined according to classes thereof, the refrigerator vehicle inevitably have a loading space left in a refrigeration trailer when carrying loads, such as ice cream, having heavy weight and small volume. 
     That is, as shown in  FIG. 2 , even when the refrigeration trailer  20  is not completely filled with loads (L), the entire inner space thereof is maintained at a low temperature, thereby causing high fuel and oil costs and overload of the refrigeration system in long-distance transportation. 
     In order to solve this problem, attempts have been made to divide an inner space of a refrigeration trailer using fixed partition walls. However, such attempts are inefficient for real-life situations in which loads are always variable in quantity and volume, and cause limitation in quantity of loads and inconvenience of a loading operation. 
     DISCLOSURE 
     Technical Problem 
     The present invention has been conceived to solve such problems in the related art and is aimed at providing a loading space variable refrigeration system of a refrigerator vehicle, which can vary a loading space in a refrigeration trailer of a refrigerator vehicle according to volume of loads. 
     Technical Solution 
     In accordance with one aspect of the present invention, a loading space variable refrigeration system of a refrigerator vehicle includes: a horizontal bulkhead defining an upper space in a refrigeration trailer; and a vertical bulkhead defining a rear space in the refrigeration trailer, wherein an uncooling region is set in a cooling space of the refrigeration trailer by the horizontal and vertical bulkheads. 
     The horizontal or vertical bulkhead may be movable. 
     The horizontal bulkhead may be moved upwards and downwards in the refrigeration trailer to set a lower cooling space to which cool air is transferred and an upper uncooling region to which cool air is not transferred. 
     The vertical bulkhead may be moved forwards and rearwards in the refrigeration trailer to set a front cooling space to which cool air is transferred and a rear uncooling region to which cool air is not transferred. 
     A plurality of horizontal bulkheads may be arranged parallel to a ceiling of the refrigeration trailer in a horizontal direction, and the horizontal bulkheads selected according to operator control or all the horizontal bulkheads may be moved downwards. 
     The horizontal bulkheads may have a plate-shaped structure made of a material to block air flow. 
     Each of the horizontal bulkheads may be provided on an upper surface thereof with an insertion portion and have inclined front and rear sides, wherein the front side may be formed as an inclined support surface supporting another horizontal bulkhead opposite thereto and the rear side may be formed as an inclined coupling surface supported by another horizontal bulkhead opposite thereto. 
     The refrigeration system may further include a hoist moving all the horizontal bulkheads or the selected horizontal bulkheads upwards and downwards, wherein the hoist may include: a control key controlled by an operator; a plurality of wires wound or unwound by rotation of the control key; and pulleys disposed above the horizontal bulkheads such that the wires are wound therearound, wherein each of the wires passing over the corresponding pulley may be secured at a distal end thereof to the corresponding horizontal bulkhead, and when the control key is rotated to unwind the wire, the horizontal bulkhead connected to the wire may be moved downwards. 
     Stopping pieces may be formed at both sides of each horizontal bulkhead facing side surfaces of the trailer, stoppers that are to be changed in position may be provided on the side surfaces of the trailer facing the stopping pieces of the horizontal bulkhead to selectively move the horizontal bulkhead downwards, and the stoppers may be switched to a lock position against the specific horizontal bulkhead such that the stopping pieces of the corresponding horizontal bulkhead are stopped by the stoppers, which prevents the horizontal bulkhead from moving downwards. 
     The horizontal bulkhead may include a plurality of unit horizontal bulkheads that are to move upwards and downwards and to be changed in position, and heights and positions of the unit horizontal bulkheads may be adjusted by operator control to conform to heights according to horizontal positions of loads in the refrigeration trailer. 
     The horizontal bulkhead may be formed of a flexible material and partially deformed by operator control to conform to heights according to horizontal positions of loads. 
     Cool air may be supplied through a cool-air supply hole provided at a front end of the refrigeration trailer and transferred to an inner space of the refrigeration trailer through a duct provided on a lower surface of the horizontal bulkhead, and a front end portion of the duct may be formed of an extensible flexible material or a bellows tube. 
     The duct may be secured to the lower surface of the horizontal bulkhead and divided into a plurality of parts that are separated from one another according to selective upward and downward movement of horizontal bulkheads, and the cool air may be discharged from the duct secured to the rearmost of the lowered horizontal bulkheads. 
     The duct may be secured to the lower surface of the horizontal bulkhead and include a main air passage formed in a longitudinal direction of the refrigeration trailer and auxiliary air passages formed at left and right sides of the main air passage, wherein the main air passage may discharge the cool air to a rear end of the refrigeration trailer, and the auxiliary air passages may discharge the cool air through a plurality of through-holes formed on side surfaces thereof. 
     The main air passage may be divided into a plurality of parts in the longitudinal direction of the refrigeration trailer, each of which may have an opening/closing door capable of discharging the cool air. 
     The vertical bulkhead which is to be rotated by a rotating shaft secured to an upper inner surface of the refrigeration trailer may normally make surface-to-surface contact with an inner surface of the trailer and, in setting an uncooling region, may be rotated about the rotating shaft and arranged parallel to a gate of the refrigeration trailer. 
     The vertical bulkhead may have a plate-shaped structure made of a material to block air flow. 
     An air blocking section formed in a concave-convex pattern corresponding to that of a bottom surface of the trailer may be attached to a lower portion of the vertical bulkhead. 
     The refrigeration system may further include a transfer apparatus moving the vertical bulkhead forwards and rearwards, wherein the transfer apparatus may include: a rail secured to a lower surface of the horizontal bulkhead; a movable guide moving forwards and rearwards along the rail; a wire provided at the movable guide, wherein the rotating shaft supporting the vertical bulkhead may be connected at an upper end thereof to the movable guide and moved forwards and rearwards by the movable guide. 
     The refrigeration system may further include a connector serving as an auxiliary upper closing member for the horizontal bulkhead. 
     The connector may have a plate-shaped structure made of a material to block air flow. 
     The connector may be suspended from the movable guide of the transfer apparatus by the wire while being parallel to a ceiling of the refrigeration trailer, moved downwards according to movement of the movable guide and operator manipulation of the wire, and inserted into an insertion portion of the horizontal bulkhead to subsidiarily determine a height of the uncooling region. 
     The vertical bulkhead may include an upper sliding plate and a lower sliding plate engaged with the upper sliding plate and sliding thereon, wherein the vertical bulkhead may be normally secured to a horizontal bulkhead side while being parallel to the horizontal bulkhead, with the upper and lower sliding plates superposed on each other, and in setting an uncooling region, erected with the lower sliding plate sliding downward on the upper sliding plate. 
     The upper sliding plate may be formed at a distal end thereof with a clamp pressing a duct, through which cool air flows, while the corresponding vertical bulkhead is erected. 
     The upper sliding plate may be formed at both sides thereof with upper foldable seals to prevent cool air from leaking to the uncooling region through both sides thereof, and the lower sliding plate may be formed at both sides thereof with lower foldable seals to prevent the cool air from leaking to the uncooling region through both the sides thereof. 
     An air blocking section formed in a concave-convex pattern corresponding to that of a bottom surface of the trailer may be attached to a distal end of the lower sliding plate. 
     The refrigeration system may further include a transfer apparatus moving the vertical bulkhead forwards and rearwards, wherein the transfer apparatus may include: a rail secured to a lower surface of the horizontal bulkhead; a movable guide moving forwards and rearwards along the rail; a wire provided at the movable guide, wherein the upper sliding plate of the vertical bulkhead may be rotatably coupled to the movable guide and moved forwards and rearwards by the movable guide. 
     The vertical bulkhead may include a plurality of panels sequentially connected to one another and formed to be bendable, wherein all the panels may be normally secured to a horizontal bulkhead side while being parallel to the horizontal bulkhead and erected to set an uncooling region. 
     Each of the panels may be formed at both sides thereof with foldable seals to prevent cool air from leaking to the uncooling region through both sides thereof. 
     An air blocking section formed in a concave-convex pattern corresponding to that of a bottom surface of the trailer may be attached to the lowermost panel of the vertical bulkhead. 
     The refrigeration system may further include a transfer apparatus moving the vertical bulkhead forwards and rearwards, wherein the transfer apparatus may include: a rail secured to a lower surface of the horizontal bulkhead; a movable guide moving forwards and rearwards along the rail; a support track coupled to the movable guide; and a clamp secured to an upper portion of the movable guide and pressing a duct through which cool air flows, wherein the upper sliding plate of the vertical bulkhead may be rotatably coupled to the movable guide and moved forwards and rearwards by the movable guide. 
     In accordance with another aspect of the present invention, a loading space variable refrigeration system of a refrigerator vehicle is provided in which an uncooling region in a refrigeration trailer is set by placing one or more space-occupying units, having an adjustable inner space, in the refrigeration trailer. 
     The space-occupying units may include spatial partition structures disposed at a ceiling of the refrigeration trailer and having an expandable inner space, and the uncooling region may be set by adjusting the inner space of the selected spatial partition structures. 
     The spatial partition structures may be normally contracted, and the uncooling region may be set by expanding the selected spatial partition structures. 
     The spatial partition structures may have side surfaces formed of a corrugated wall to be folded or unfolded. 
     Each of the spatial partition structures may be provided at an upper portion thereof with an inner pulley, a wire passing over the inner pulley may be secured at one end thereof to a lower wall of the spatial partition structure and at the other end thereof to a control key via an outer pulley outside the spatial partition structure such that tension of the wire may be controlled through the control key to adjust volume of the spatial partition structure. 
     Advantageous Effects 
     According to the invention, a loading space in a refrigeration trailer of a refrigerator vehicle can be varied depending upon volume of loads, thereby reducing fuel and oil costs for cool-air supply and preventing overload of the refrigeration system. 
     In addition, a loading space can be rapidly varied only through simple operator manipulation such that separate labor is not required for loading or variation in loading space, thereby reducing entire workforce and costs. 
     Further, the refrigeration system having a variable loading space according to the present invention can be installed and operated without loss of a loading space due to small volume thereof in the trailer. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view of a typical refrigeration trailer. 
         FIG. 2  is a view showing an unreasonable cooling method for the typical refrigeration trailer. 
         FIG. 3  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to the present invention. 
         FIG. 4  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a first embodiment of the present invention. 
         FIG. 5  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
         FIGS. 6 to 16  are views showing detailed operation of the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
         FIG. 17  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a second embodiment of the present invention. 
         FIG. 18  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
         FIGS. 19 to 26  are views showing detailed operation of the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
         FIG. 27  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a third embodiment of the present invention. 
         FIG. 28  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. 
         FIGS. 29 to 33  are views showing detailed operation of the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. 
         FIG. 34  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a fourth embodiment of the present invention. 
         FIG. 35  is a view showing various operations of the loading space variable refrigeration system of a refrigerator vehicle according to the fourth embodiment of the present invention. 
         FIG. 36  is a view showing detailed operation of a spatial partition structure in the loading space variable refrigeration system of a refrigerator vehicle according to the fourth embodiment of the present invention. 
         FIGS. 37 and 38  are views showing a loading space variable refrigeration system of a refrigerator vehicle according to a fifth embodiment of the present invention. 
     
    
    
     BEST MODE 
     Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the accompanying drawings. It should be noted that like reference numerals denote like elements or components having the same or similar functions in the drawings. In the description of the present invention, detailed descriptions related to well-known functions or configurations will be omitted when they may unnecessarily obscure subject matters of the present invention. 
       FIG. 3  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to the present invention. 
     As shown in  FIG. 3(a) , a refrigeration trailer  20  having an enclosure shape is provided at a loading station of a refrigerator vehicle carrying various types of frozen or low-temperature foods/goods that cannot be stored or carried at room temperature. The refrigerator vehicle is provided with a refrigerator at a head side thereof or at one upper side of the refrigeration trailer, and the inside of the refrigeration trailer is maintained at a low temperature by an evaporator of the refrigerator. In this case, cool air is discharged into the refrigeration trailer  20  by an exhaust fan. 
     Therefore, the entire inner space of the refrigeration trailer is a cooling space (A) in which refrigeration is performed. 
     Loads, such as frozen or low-temperature foods, are loaded in the refrigeration trailer  20 . Depending upon circumstances, the refrigeration trailer  20  may be filled up with loads (L) as shown in  FIG. 3(b)  or partially filled with loads (L) as shown in  FIG. 3(c) . 
     When the refrigeration trailer  20  is filled with the loads (L) as shown in  FIG. 3(b) , the cooling space (A) within the refrigeration trailer  20  is the same as the volume of the loads (L), and therefore there are no serious problems. In contrast, when the refrigeration trailer  20  is partially filled with the loads (L) as shown in  FIG. 3(c) , there is a large difference between the cooling space (A) within the refrigeration trailer  20  and the volume of the loads (L), thereby causing a variety of problems. 
     The refrigeration system for the refrigeration trailer  20  supplies cool air into the refrigeration trailer  20  to maintain the entire inner space thereof at a predetermined temperature regardless of the quantity and volume of the loads (L). Therefore, even when loads (L) are small in quantity and volume, the refrigeration system cools the entire inner space of the refrigeration trailer  20 , namely, the cooling space (A), thus causing increase in fuel and oil cost and overload of the refrigeration system. 
     The present invention has been conceived to solve such problems. In the present invention, a loading space may be varied by reducing the internal cooling space (A) of the refrigeration trailer  20  depending upon circumstances. For example, when loads (L) are small in quantity and volume as shown in  FIG. 3(d) , an uncooling region (B) is increased, and the refrigeration system cools only the reduced cooling space (A). 
     Hereinafter, various embodiments of the present invention for reducing a cooling space (A) by increasing an uncooling region (B) will be described with reference to the accompanying drawings. 
     The uncooling region (B) may be set by a horizontal bulkhead moving in an upper space of the refrigeration trailer  20  to define an upper space of the uncooling region (B) and a vertical bulkhead moving in a rear space of the refrigeration trailer  20  to define a rear space of the uncooling region (B). The horizontal bulkhead may be constituted by a single or a plurality of horizontal bulkheads parallel to the horizontal section (e.g., the ceiling) of the refrigeration trailer  20  such that a space above loads (L) is defined and blocked. The vertical bulkhead may be constituted by a gate parallel to the vertical section of the refrigeration trailer  20  (e.g., an opening/closing door of the refrigeration trailer) such that a space behind the loads (L) is defined and blocked. Specific examples of setting the uncooling region (B) will be described below in detail through the following embodiments 1 to 3. 
     That is, the horizontal bulkhead is moved upwards and downwards within the refrigeration trailer  20  to set a lower cooling space (A) to which cool air is transferred and an upper uncooling region (B) to which cool air is not transferred. 
     The vertical bulkhead is moved forwards and rearwards within the refrigeration trailer  20  to set a front cooling space (A) to which cool air is transferred and a rear uncooling region (B) to which cool air is not transferred. 
     In addition, such an uncooling region (B) may also be set by expanding a plurality of balloons disposed on wall faces of the refrigeration trailer  20 . Specific examples of setting the uncooling region (B) in such a manner will be described in detail in a fourth embodiment of the present invention. 
     Embodiment 1 
       FIG. 4  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a first embodiment of the present invention. 
     In the first embodiment of the present invention, an uncooling region (B) in a refrigeration trailer  20  is set by a plurality of horizontal bulkheads  110  moving upwards and downwards and a vertical bulkhead  120  moving forwards and rearwards and operating as a hinged gate. A connector  130  complements deficiency in length of the lowered horizontal bulkheads  110 . 
     The horizontal bulkheads  110  are arranged parallel to the ceiling of the refrigeration trailer  20  in the horizontal direction. The horizontal bulkheads  110  are selectively moved downwards according to operator manipulation of a hoist, and the height of the uncooling region (B) is determined by a vertical distance by which the horizontal bulkheads  110  move downwards. 
     More specifically, the horizontal bulkheads  110  are plate-shaped structures formed of a material to block air flow. Each of the horizontal bulkheads  110  is provided on the upper surface thereof with an insertion portion  111  into which one portion of the connector  130  may be inserted. In addition, the horizontal bulkhead  110  has inclined front and rear sides. As shown in  FIG. 4 , the front side of the horizontal bulkhead  110  (a tractor side of a refrigerator vehicle, more specifically, a cool-air supply side through which cool air is discharged) is formed as an inclined support surface  112  supporting another horizontal bulkhead  110  opposite thereto, and the rear side of the horizontal bulkhead  110  is formed as an inclined coupling surface  113  supported by another horizontal bulkhead  110  opposite thereto. Therefore, thank to the inclined assembly structure of the horizontal bulkhead  110 , the preceding horizontal bulkhead  110  can be moved downwards before the following horizontal bulkhead  110 , thereby preventing the following horizontal bulkhead  110  from moving downwards before the preceding horizontal bulkhead  110 . Further, stopping pieces  114  are formed on surfaces of the horizontal bulkhead  110  facing side surfaces of the refrigeration trailer  20 . 
     The horizontal bulkheads  110  are selectively moved upwards or downwards by the hoist  150 . The hoist  150  includes a control key  151  controlled by an operator, a plurality of wires  152  wound or unwound by rotation of the control key  151 , and pulleys  153  disposed above the horizontal bulkheads  110  such that the wires  152  are wound therearound, respectively. Each of the wires  152  passing over the pulley  153  is secured at a distal end thereof to the horizontal bulkhead  110 . 
     Accordingly, when an operator unwinds the wires  152  by rotating the control key  151 , the corresponding horizontal bulkhead  110  connected to the wires  152  is moved downwards. In order to selectively move the horizontal bulkheads  110  downwards, stoppers  155 , a position of which may be changed, are provided on the side surfaces of the refrigeration trailer  20  facing the stopping pieces  114  of the horizontal bulkheads  110 . An operator may switch the stoppers  155  to a lock position against the specific horizontal bulkhead  110  such that the stopping pieces  114  of the horizontal bulkhead  110  are stopped by the stoppers  155 , thereby preventing the horizontal bulkhead from moving downwards. In contrast, the operator may switch the stoppers  155  to an unlock position for the specific horizontal bulkhead  110  to prevent the stopping pieces  114  of the horizontal bulkhead  110  from being stopped by the stoppers  155 , thereby allowing the horizontal bulkhead to move downwards. The control key  151  allows the horizontal bulkhead  110  to move upwards or downwards by controlling the length of the wires  152 . Details of this process will be understood through the following description. 
     Cool air is supplied to the trailer  20  through a cool-air supply hole  191  provided at a front end thereof and transferred to an inner space of the trailer  20  through a duct  190  provided on lower surfaces of the horizontal bulkheads  110 . A front end portion of the duct  190  may be formed of an extensible flexible material (e.g., a fabric) or a bellows tube not to be affected by upward and downward movement of the horizontal bulkheads  110 . The duct  190  is secured to the lower surfaces of the horizontal bulkheads  110 . The duct  190  may be divided into a plurality of parts, and the parts of the duct may be separated from one another when the horizontal bulkheads  110  are moved downwards and upwards. In this case, among the plural duct parts, the rearmost duct part discharges cool air. In another example, the duct  190  may be open at some portions of left and right sides thereof and at a distal end thereof. Some cool air is supplied to loads (L) through the left and right openings, and the rest is supplied through the distal opening to the inner space of the refrigeration trailer  20  and circulates therein. The duct structure in which a duct is divided into plural parts to correspond to bulkheads may also be applied to this example. 
     The vertical bulkhead  120  is a plate-shaped structure formed of a material to block air flow. The vertical bulkhead  120  may be rotated by a rotating shaft  121  secured to an upper inner surface of the trailer  20 . The vertical bulkhead  120  normally makes surface-to-surface contact with the inner surface of the trailer  20  and in setting the uncooling region (B), is rotated about the rotating shaft  121  and arranged parallel to a gate of the trailer  20 . 
     The number of vertical bulkheads  120  may vary with the vertical cross-sectional area of the trailer  20 . For example, when the trailer  20  has a small vertical cross-sectional area, one vertical bulkhead  20  having a vertical cross-sectional area corresponding to that of the trailer  20  may be opened and closed by a single rotating shaft  121  provided at one side surface of the trailer  20 . In contrast, when the trailer  20  has a large vertical cross-sectional area, two vertical bulkheads  20  having a vertical cross-sectional area corresponding to half that of the trailer  20  may be opened and closed by two rotating shafts  121  provided at both side surfaces of the trailer  20 . That is, the vertical bulkheads  120  are hinged gates opened and closed by the rotating shafts  121 . 
     An air blocking section  122  may be attached to a lower portion of the vertical bulkheads  120 . The bottom surface of the trailer  20  has a concave-convex pattern such that air circulates therethrough. Therefore, the vertical bulkheads  120  are to be formed at the lower portion thereof with the air blocking section  122  to prevent cool air from being discharged through the concave-convex pattern. The air blocking section  122  may have a concave-convex pattern corresponding to that of the bottom surface of the trailer  20  and be formed of a flexible material (e.g., sponge) not to disturb rotary motion of the vertical bulkheads  120 . 
     The vertical bulkheads  120  are transferred forwards and rearwards by a transfer apparatus  160 . The transfer apparatus  160  includes rails  161  secured to the lower surfaces of the horizontal bulkheads  110 , a movable guide  162  moving forwards and rearwards along the rails  161 , and wires  164  attached to the movable guide  162 . The rotating shafts  121  supporting the vertical bulkheads  120  are connected at an upper end thereof to the movable guide  162  to move forwards and rearwards. 
     The movable guide  162  is placed on rollers  163  and smoothly slides along the rails  161 . 
     Therefore, the vertical bulkheads  120  are moved along the rails  161  and then closed. As a result, the range of the uncooling region (B) is determined by a moving distance of the vertical bulkheads  120 . 
     The horizontal bulkheads  110  have a predetermined length, and therefore an auxiliary upper closing member is required to freely set the desired cooling space (A). To this end, the refrigeration system according to the first embodiment of the present invention includes the connector  130 . 
     The connector  130  is a plate-shaped structure formed of a material to block air flow. The connector  130  is suspended from the movable guide  162  of the transfer apparatus  160  by the wires  164  while being parallel to the ceiling of the refrigeration trailer  20 . More specifically, for convenience of coupling to the horizontal bulkhead  110  after movement, the connector  130  is suspended from the movable guide  162  by the wires  164  while being inserted into a casing  132 . The connector  130  is moved downwards according to movement of the movable guide  162  and operator manipulation of the wires  164  and then, is inserted into the insertion portion  111  of the rearmost horizontal bulkhead  110 , thereby subsidiarily determining the height of the uncooling region (B). 
     Operation of the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention having the structure as described above will be specifically described below with reference to  FIG. 5  briefly showing the overall operation and  FIGS. 6 to 16  showing detailed operation. 
       FIG. 5  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     Referring to  FIG. 5 , among the plural horizontal bulkheads  110 , the horizontal bulkheads  110  above loads (L) are selected and moved downwards to the height of the loads (L) to set an uncooling region (B) above the loads (L) (See  FIG. 5(a) ). The connector  130  is moved downwards to the height of the lowered horizontal bulkheads  110  (See  FIG. 5(b) ). The connector  130  and the vertical bulkheads  120  are moved to the distal end of the loads (L) (See  FIG. 5(c) ). The connector  130  is coupled to the rearmost lowered horizontal bulkhead  110  to completely set the uncooling region (B) above the loads (See  FIG. 5(d) ). The vertical bulkheads  120  are rotated to set the uncooling region (B) behind the loads (L) (See  FIG. 5(e) ). The overall operation of varying the loading space is completed. 
       FIG. 6  is a view showing an operation of moving the horizontal bulkheads  110  downwards in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
       FIG. 6(a)  shows the horizontal bulkheads  110  in a standby state. The horizontal bulkheads  110  are positioned near the ceiling of the refrigeration trailer  20 . 
       FIG. 6(b)  shows the horizontal bulkhead  110  moving downwards among the plural horizontal bulkheads  110 . When each of the wires  152  is unwound through operator manipulation of the control key  151 , a support  154  connected to the distal end of the wire  152  is moved downwards, and the horizontal bulkhead  110  with the stopping piece  114  placed on the support  154  is moved downwards. 
       FIG. 6(c)  shows the horizontal bulkhead  110  not moving downwards among the plural horizontal bulkheads  110 . An operator switches in advance the stopper  155  to a lock position such that the stopping piece  114  is stopped by the stopper  155 . As a result, even though the wire  152  is unwound, the corresponding horizontal bulkhead  100  does not move downwards. 
       FIG. 7  is a view showing an operation of selectively moving horizontal bulkheads  110 A,  110 B downwards in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
       FIG. 7(a)  shows the horizontal bulkheads  110 A,  110 B in a standby state. The adjacent horizontal bulkheads  110 A,  110 B are positioned near the ceiling of the refrigeration trailer  20 . In this case, the horizontal bulkheads  110 A,  110 B are coupled to each other through a locking bar  115  inserted thereinto. 
       FIG. 7(b)  shows a state in which the left  110 A of the horizontal bulkheads  110 A,  110 B is moved downwards. An operator unlocks the adjacent horizontal bulkheads  110 A,  110 B by moving the locking bar  115  rearwards. When the wire  152  is unwound through operator manipulation of the control key  151 , the left horizontal bulkhead  110 A is moved downwards together with a support  154 A at the distal end of the wire  152 . In this case, a stopper  155 A is switched to an unlock position for the left horizontal bulkhead  110 A, and a stopper  155 B is switched to a lock position against the right horizontal bulkhead  110 B. Therefore, only the left horizontal bulkhead  110 A can be selectively moved downwards. The stoppers  155 A,  155 B may be switched in advance by an operator. 
       FIG. 8  is a view showing a standby state of the vertical bulkheads  120  and the connector  130  in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     The two vertical bulkheads  120  are normally disposed near both the side surfaces of the refrigeration trailer  20 , respectively, and the connector  130  is inserted into the casing  132  secured by the wires  164  to the movable guide (not shown) on the rails  161 . 
       FIG. 9  is a view showing an operation of moving the connector  130  downwards in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention.  FIGS. 9(a) and 9(b)  are front and side views showing a state in which the connector  130  is moved downwards. 
     Referring to  FIG. 9 , when the wires  164  are unwound by an operator, the casing  132  secured to the movable guide  162  on the rails  161  is slowly is moved downwards. In this case, a vertical distance that the casing  132  moves downwards may be adjusted by the operator depending upon the vertical distance by which the horizontal bulkheads  110  have moved downwards. 
       FIGS. 10 to 12  are views showing an operation of coupling the connector  130  to the horizontal bulkhead  110  in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     Referring to  FIG. 10 , the movable guide  162  supporting the lowered connector  130  is moved forwards along the rails  161 , and thus, the casing  132  receiving the connector  130  therein closely approaches the horizontal bulkhead  110 . 
     Referring to  FIG. 11 , the connector  130  is extracted from the casing  132 , and one portion of the connector  130  is inserted into the insertion portion  111  of the horizontal bulkhead  110 . As a result, the connector  130  is coupled to the horizontal bulkhead  110 . 
     Referring to  FIG. 12 , the casing  132  retreats by moving the movable guide  162  rearwards along the rails  161 . Thereafter, a space is ensured by moving the casing  132  upwards again. 
       FIGS. 13 and 14  are views showing a post-process after the connector  130  is coupled to the horizontal bulkhead  110  in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     When the connector  130  overhangs the loads (L) as shown in  FIG. 13 , the connector  130  is pushed to fit the length of the loads (L). 
       FIG. 15  is a view showing an operation of moving the vertical bulkheads  120  in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     The vertical bulkheads  120  secured to the movable guide  162  are moved to the distal end of the connector  130  according to movement of the movable guide  162  and rotated by the rotating shafts  121  to close the cooling space (A) as shown in  FIG. 15 . 
     Reference numeral  131  not described herein denotes an air blocking section for sealing a space between the connector  130  and the vertical bulkheads  120 . 
       FIG. 16  is a view showing an operation of sealing the bottom of the vertical bulkheads  120  in the loading space variable refrigeration system of a refrigerator vehicle according to the first embodiment of the present invention. 
     As described above, the bottom surface of the trailer  20  has a concave-convex pattern such that air circulates therethrough. Therefore, the vertical bulkheads  120  are to be formed at the lower portion thereof with the air blocking section  122  to prevent cool air from being discharged therethrough. The air blocking section  122  includes seal brushes  124  arranged in a concave-convex pattern to correspond to the concave-convex pattern of the bottom surface of the trailer  20  and a rotating rod  123  for rotating the seal brushes  124 . When rotated upwards about the rotating rod  123  and secured, the seal brushes  124  do not affect movement of the vertical bulkheads  120 . In contrast, when rotated downwards about the rotating rod  123  and secured, the seal brushes  124  are inserted into depressions of the concave-convex pattern formed on the bottom surface of the trailer  20  to prevent cool air from being exhausted from the cooling space (A). The seal brushes may be formed of a flexible material (e.g., sponge). 
     Embodiment 2 
       FIG. 17  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a second embodiment of the present invention. 
     In the second embodiment of the present invention, an uncooling region (B) in a refrigeration trailer  20  is set by a single or a plurality of horizontal bulkheads  210  moving upwards and downwards and a vertical bulkhead  220  moving forwards and rearwards and operating as a sliding gate in which a lower wall is engaged with an upper wall and slides thereon. 
     The second embodiment is different from the first embodiment in that the connector  130  is not necessary. 
     In description of the second embodiment, repetitious description of components having the same configuration as in the first embodiment will be omitted, and the following description focuses on the differences from the first embodiment. 
     The horizontal bulkheads  210  in the second embodiment have a configuration similar to the horizontal bulkheads  110  in the first embodiment. However, in the first embodiment, only some of the horizontal bulkheads  110  are moved downwards to set the uncooling region (B), whereas in the second embodiment, all the horizontal bulkheads  210  may be are moved downwards to set the uncooling region (B). Therefore, in the second embodiment, a single horizontal bulkhead may also be provided to cover a horizontal space in the refrigeration trailer  20 , instead of the plural horizontal bulkheads  210 . 
     Cool air is supplied to the refrigeration trailer  20  through a cool-air supply hole  291  provided at a front end thereof and transferred to an inner space of the refrigeration trailer  20  through a duct  290 . The duct  290  has a structure in which a main air passage  292  is formed in a longitudinal direction of the refrigeration trailer  20 , and auxiliary air passages  293 ,  294  are formed at left and right sides of the main air passage  292 . The main air passage  292  is used to discharge cool air to a rear end portion of the refrigeration trailer  20 , and the auxiliary air passages  293 ,  294  are used to partially supply the cool air to a lower space of the refrigeration trailer  20  by discharging the cool air through through-holes  296  formed on side surfaces thereof. Particularly, in this embodiment, the main air passage  292  of the duct  290  may be divided into a plurality of parts in the longitudinal direction of the refrigeration trailer  20 , each of which has an opening/closing door  295 . Therefore, when an operator opens the opening/closing door  295  of a specific part, the cool air supplied through the cool-air supply hole  291  at the front end of the trailer  20  is discharged from the corresponding position through the opening/closing door  295  to the inner space of the refrigeration trailer  20 . The duct  290  will be described below in detail with reference to the related drawings. 
     The vertical bulkhead  220  is a structure in which a lower sliding plate  223  is engaged with an upper sliding plate  221  and slides thereon, and the upper and lower sliding plates  221 ,  223  are made of a material to block air flow. More specifically, the upper and lower sliding plates  221 ,  223  are coupled while facing each other, and the lower sliding plate  223  slides on the upper sliding plate  221 . A transfer apparatus  260  is provided on the lower surface of the horizontal bulkhead  210  to move the vertical bulkhead  220  forwards and rearwards. The vertical bulkhead  220  stands by while making surface-to-surface contact with the lower surface of the horizontal bulkhead  210  and is moved forwards by the transfer apparatus  260 , with the upper and lower sliding plates  221 ,  223  superposed on each other. Thereafter, the vertical bulkhead  220  rotates to a vertical position and sets the uncooling region (B), with the lower sliding plate  223  sliding downwards on the upper sliding plate  221 . That is, the vertical bulkhead  220  is a type of sliding gate in which the lower sliding plate  223  is engaged with the upper sliding plate  221  and slides thereon. The upper sliding plate  221  is formed at a distal end thereof with a clamp  225  pressing the main air passage  292  and the auxiliary air passages  293 ,  294  of the duct  290  when the vertical bulkhead  220  rotates to the vertical position. In addition, the upper sliding plate  221  is formed at both sides thereof with upper foldable seals  222  to prevent cool air from leaking to the uncooling region (B) through both sides thereof. Like the upper sliding plate  221 , the lower sliding plate  223  is formed at both sides thereof with lower foldable seals  224  to prevent cool air from leaking to the uncooling region (B) through both sides thereof. In addition, the lower sliding plate  223  is formed at a distal end thereof with an air blocking section  226  to prevent cool air from leaking to the uncooling region (B). The air blocking section  226  prevents leakage of cool air through a concave-convex pattern at the bottom of the refrigeration trailer  20  as in the first embodiment. 
     The vertical bulkhead  220  is moved forwards and rearwards by the transfer apparatus  260 . The transfer apparatus  260  includes rails  261  secured to the lower surface of the horizontal bulkhead  210 , a movable guide  262  moving forwards and rearwards along the rails  261 , and a wire  264  attached to the movable guide  262 . The upper sliding plate  221  of the vertical bulkhead  220  is rotatably coupled to the movable guide  262 . 
     The movable guide  262  is placed on rollers  263  to smoothly slide along the rails  261 . 
     Therefore, the vertical bulkhead  220  having moved along the rails  261  rotates to a vertical position and then spreads. As a result, the range of the uncooling region (B) is determined by a moving distance of the vertical bulkhead  220 . 
     Operation of the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention having the structure as described above will be specifically described below with reference to  FIG. 18  briefly showing overall operation of the refrigeration system and  FIGS. 19 to 26  showing detailed operation. 
       FIG. 18  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
     Referring to  FIG. 18 , when loads (L) are loaded in the refrigeration trailer  20  (See  FIG. 18(a) ), the main air passage  292  at the distal end of the loads (L) is open and the vertical bulkhead  220  is moved to the distal end of the loads (L) (See  FIG. 18(b) ). The vertical bulkhead  220  is rotated to a vertical position, and the clamp  225  presses the main air passage  292  and the auxiliary air passages  293 ,  294  at the distal end of the loads (L) (See  FIG. 18(c) ). The vertical bulkhead  220  extends downwards by sliding the lower sliding plate  223  (See  FIG. 18(d) ). The horizontal bulkheads  210  are moved downwards to the height of the loads (L) (See  FIG. 18(e) ). The overall operation of varying the loading space is completed. 
     Although the horizontal bulkheads  210  are moved downwards after installation of the vertical bulkhead  220 , the horizontal bulkheads  210  may also be moved downwards before installation of the vertical bulkhead  220 . 
       FIG. 19  is a view showing an operation of supplying cool air through the duct  290  in the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
       FIG. 19(a)  shows an intermediate portion of the entire duct  290 . The duct  290  has a structure in which the main air passage  292  is formed in the longitudinal direction of the refrigeration trailer  20 , and the auxiliary air passages  293 ,  294  are formed at the left and right sides of the main air passage  292 . The main air passage  292  is used to discharge cool air to the rear end portion of the refrigeration trailer  20 , and the auxiliary air passages  293 ,  294  are used to partially supply the cool air to the lower space of the refrigeration trailer  20  by discharging the cool air through the plural through-holes  296  formed on the side surfaces thereof. 
       FIG. 19(b)  shows a distal end portion of the entire duct  290 . In this embodiment, the main air passage  292  of the duct  290  may be divided into a plurality of parts in the longitudinal direction of the refrigeration trailer  20 , each of which has the opening/closing door  295 . Therefore, when an operator opens the opening/closing door  295  of a specific part, the cool air supplied through the cool-air supply hole  291  at the front end of the trailer  20  is discharged from the corresponding position through the opening/closing door  295  to the inner space of the refrigeration trailer  20 . 
       FIG. 19(c)  shows a cool-air supply structure of the entire duct  290 . The supplied cool air is transferred to the rear end side of the refrigeration trailer  20  through the main air passage  292  of the duct  290  and at the same time, partially discharged through the auxiliary air passages  293 ,  294  of the duct  290  in the entire region of the refrigeration trailer  20 . In this case, when the opening/closing door  295  at a specific position of the main air passage  292  is open, the cool air is discharged downwards and circulates in the entire space. 
       FIG. 20  is a view showing a structure of the vertical bulkhead  220  in the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
       FIG. 20(a)  is a rear view of the vertical bulkhead  220 , and  FIG. 20(b)  is a side view of the vertical bulkhead  220 . The vertical bulkhead  220  stands by while making surface-to-surface contact with the lower surface of the horizontal bulkhead  210 . As shown in  FIG. 20 , the upper and lower sliding plates  221 ,  223  of the vertical bulkhead  220  are superposed on each other. The upper foldable seals  222  at both the sides of the upper sliding plate  221  and the lower foldable seals  224  at both the sides of the lower sliding plate  223  are folded. The upper sliding plate  221  is formed at the distal end thereof with the clamp  225  pressing the main air passage  292  and the auxiliary air passages  293 ,  294  of the duct  290  when the vertical bulkhead  220  rotates to the vertical position. Here, reference numeral  264  denotes a wire used to move the vertical bulkhead  220 . 
       FIG. 21  is a view showing the foldable seals of the vertical bulkhead  220  in the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
       FIG. 21(a)  shows the upper sliding plate  221 . The upper sliding plate  221  is formed at both sides thereof with the upper foldable seals  222  to prevent cool air from leaking to the uncooling region (B) through both sides thereof. In addition, the upper sliding plate  221  is formed at the distal end thereof with the clamp  225  pressing the main air passage  292  and the auxiliary air passages  293 ,  294  of the duct  290  when the vertical bulkhead  220  rotates to the vertical position. 
       FIG. 21(b)  shows the lower sliding plate  221 . The lower sliding plate  223  is formed at both sides thereof with the lower foldable seals  224  to prevent cool air from leaking to the uncooling region (B) through both sides thereof. 
       FIG. 22  is a view showing an operation of installing the vertical bulkhead  120  in the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
     Referring to  FIG. 22 , the vertical bulkhead  220  is moved to the position of the loads (L) by moving the movable guide  262  supporting the vertical bulkhead  220  along the rails  261 , and the opening/closing door  295  of the main air passage  292  above the loads (L) is open. 
     Referring to  FIG. 23 , the vertical bulkhead  220  is rotated to a vertical position, whereby the clamp  225  of the upper sliding plate  221  presses the main air passage  292  and the auxiliary air passages  293 ,  294  of the duct  290 . 
     Referring to  FIG. 24 , the lower sliding plate  223  of the vertical bulkhead  220  is moved downwards, and the air blocking section  226  is secured to the bottom of the refrigeration trailer  20 . The air blocking section  226  has the same configuration as that of the first embodiment. 
       FIGS. 25 and 26  are views showing an operation of preventing leakage of cool air by the vertical bulkhead  220  in the loading space variable refrigeration system of a refrigerator vehicle according to the second embodiment of the present invention. 
       FIG. 25  is a rear view showing a state in which the vertical bulkhead  220  is rotated to a vertical position. 
     Referring to  FIG. 26(a) , the lower foldable seals  224  at both sides of the lower sliding plate  223  are unfolded to contact inner side surfaces of the refrigeration trailer  20 , and the air blocking section  226  is provided at the lower end of the lower sliding plate  223  such that seal brushes  228  thereof are inserted into depressions of the concave-convex pattern at the bottom of the trailer  20  to prevent cool air from being exhausted from the cooling space (A). 
     Referring to  FIG. 26(b) , after the vertical bulkhead  210  is moved downwards, the upper foldable seals  224  at both sides of the upper sliding plate  223  are unfolded to contact the inner side surfaces of the refrigeration trailer  20 , thereby separating the entire cooling space (A) from the uncooling region (B). 
     Embodiment 3 
       FIG. 27  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a third embodiment of the present invention. 
     In the third embodiment of the present invention, an uncooling region (B) in a refrigeration trailer  20  is set by a single or a plurality of horizontal bulkheads  310  moving upwards and downwards and a vertical bulkhead  320  moving forwards and rearwards and operating as a roll-up gate moving upwards and downwards along tracks. 
     The third embodiment is different from the first embodiment in that the connector  130  is not necessary. 
     In description of the third embodiment, repetitious description of components having the same configuration as in the first and second embodiments will be omitted, and the following description is focused on the difference from the first and second embodiments. 
     The horizontal bulkheads  310  in the third embodiment have configuration similar to the horizontal bulkheads  110 ,  210  in the first and second embodiments. Particularly, the horizontal bulkheads  310  have the same configuration as those in the second embodiment in that all the horizontal bulkheads  310  are moved downwards to set the uncooling region (B). 
     Cool air is supplied to the refrigeration trailer  20  through a cool-air supply hole  391  provided at a front end thereof and transferred to an inner space of the refrigeration trailer  20  through a duct  390 . The duct  390  in the third embodiment has the same configuration as the duct  290  in the second embodiment. 
     The vertical bulkhead  320  is a bendable structure in which a plurality of panels  322  made of a material to block air flow is sequentially connected to one another. More specifically, a connection part between the panels  322  may be bent by a hinge embedded therein and is provided with wheels  323 . The vertical bulkhead  320  is supported by a support track  321  coupled to a transfer apparatus  360 . The vertical bulkhead  320  normally stands by while being slid into the support track  321 . Thereafter, the vertical bulkhead  320  is dragged down from the support track  321  and erected, thereby setting the uncooling region (B). That is, the vertical bulkhead  320  is a type of roll-up gate sliding along the support track  321 . Each panel  322  of the vertical bulkhead  320  is formed at both sides thereof with foldable seals  324  to prevent cool air from leaking to the uncooling region (B) through both sides thereof. The panels  322  of the vertical bulkhead  320  may have different sizes for efficiency in operation. In addition, an air blocking section  326  for preventing leakage of cool air to the uncooling region (B) is formed at the distal panel  322  of the vertical bulkhead  320 . The air blocking section  326  prevents leakage of cool air through a concave-convex pattern at the bottom of the refrigeration trailer  20  as in the first and second embodiments. 
     The vertical bulkhead  320  is moved forwards and rearwards by the transfer apparatus  360 . The transfer apparatus  360  includes rails  361  secured to the lower surface of the horizontal bulkhead  310  and a movable guide  362  moving forwards and rearwards along the rails  361 . The support track  321  is coupled to the movable guide  362 , and when the movable guide  362  moves, the support track  321  and the vertical bulkhead  320  are moved together. 
     The movable guide  362  is placed on rollers  363  to smoothly slide along the rails  361 . 
     The vertical bulkhead  320  on the support track  321  having moved along the rails  361  is dragged down, and the range of the uncooling region (B) is determined by a moving distance of the vertical bulkhead  320 . 
     Operation of the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention having the structure as described above will be specifically described below with reference to  FIG. 28  briefly showing overall operation of the refrigeration system and  FIGS. 29 to 33  showing detailed operation. 
       FIG. 28  is a view schematically showing overall operation of the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. 
     Referring to  FIG. 28 , when loads (L) are loaded in the refrigeration trailer  20 , a main air passage  392  above the distal end portion of the loads (L) is open, and the vertical bulkhead  320  is moved to the distal end portion of the loads (L) by moving the movable guide  362  (See  FIG. 28(a) ). The horizontal bulkheads  310  are moved downwards to the height of the loads (L), together with the vertical bulkhead  320  connected thereto (See  FIG. 28(b) ). The vertical bulkhead  320  is dragged down such that a vertical length thereof is increased (See  FIG. 28(c) ). The overall operation of varying the loading space is completed. 
     As shown in  FIG. 28(c) , a clamp  365  on the movable guide  362  blocks off the main air passage  292  and auxiliary air passages  393 ,  394  above the distal end portion of the loads (L). 
     Although the vertical bulkhead  320  is installed after downward movement of the horizontal bulkheads  310 , the vertical bulkhead  320  may also be installed before downward movement of the horizontal bulkheads  310 . 
       FIG. 29  is a view showing a structure of the vertical bulkhead  220  in the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. 
       FIG. 29(a)  is a rear view showing the vertical bulkhead  220 . Each of the horizontal bulkheads  320  is provided at both lower sides thereof with the rails  361 , and the movable guide  362  is moved forwards and rearwards along the rails  361 . The support track  321  is secured to the movable guide  362 , and when the movable guide  362  moves, the support track  321  is also moved forwards and rearwards together. The wheels  323  of the shutter panels  322  constituting the vertical bulkhead  320  are embedded in the support track  321 . Here, reference numeral  324  denotes foldable seals formed at both sides of each panel  322  to prevent leakage of cool air to the uncooling region (B) through both sides thereof. 
       FIG. 29(b)  is a side view showing a state in which the shutter panels  322  constituting the vertical bulkhead  320  are parallel to the ceiling, namely, the horizontal bulkheads  310 . The shutter panels  322  are moved along the support track  321 , one portion of which is parallel to the horizontal bulkheads  310  and the other portion of which is perpendicular to the horizontal bulkheads  310 . Therefore, although the shutter panels  322  does not play a role when placed at the portion of the support track  321  parallel to the horizontal bulkheads  310 , the shutter panels  322  act as walls for blocking cool air moving in the vertical direction when placed at the portion of the support track  321  perpendicular to the horizontal bulkheads  310 . 
       FIG. 30  is a plan view showing a state in which the vertical bulkhead  320  is parallel to the ceiling, namely, the horizontal bulkheads  310  in the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. In  FIG. 31 , the shutter panels  322  having different sizes are not yet moved downwards. 
       FIG. 31  is a plan view showing a state in which one portion of the vertical bulkhead  320  is moved downwards in the loading space variable refrigeration system of a refrigerator vehicle according to the third embodiment of the present invention. Referring to  FIG. 31 , some of the shutter panels  322  are moved downwards along the support track  321 , as compared with  FIG. 30 . Accordingly, the rearmost opening/closing door  395  of the main air passage  392  is open, and the main air passage  392  and the auxiliary air passages  393 ,  394  above the distal end portion of the loads (L) are blocked by the clamp  365  of the moved transfer apparatus  360 , such that cool air may be transferred only to the cooling space (A) in the refrigeration trailer  20 . 
     In  FIG. 32 , for better understanding, the vertical bulkhead  320  is moved downwards and erected without downward movement of the horizontal bulkheads  310 , thereby setting the uncooling region (B). In contrast, in  FIG. 33 , the vertical bulkhead  320  is moved downwards and erected after downward movement of the horizontal bulkheads  310 , thereby setting the uncooling region (B). As shown in  FIGS. 32 and 33 , the foldable seals  324  at both sides of each shutter panel  322  constituting the vertical bulkhead  320  are unfolded to contact the inner side surfaces of the refrigeration trailer  20 , and the air blocking section  326  is provided at the lower end of the lowermost shutter panel such that seal brushes  328  thereof are inserted into depressions of the concave-convex pattern at the bottom of the trailer  20  to prevent cool air from being exhausted from the cooling space (A). 
     Embodiment 4 
       FIG. 34  is a view of a loading space variable refrigeration system of a refrigerator vehicle according to a fourth embodiment of the present invention. 
     In the fourth embodiment of the present invention, an uncooling region (B) in a refrigeration trailer  20  is set by placing one or more space-occupying units, having an adjustable inner space, in the refrigeration trailer. 
     The space-occupying units are characterized by the inner space in which cooling is not performed, and a space to be cooled is reduced simply by adjusting the number and volume of space-occupying units present in the refrigeration trailer. 
     Here, any unit that can be disposed at the ceiling of the trailer and adjusted by expanding an inner space thereof, such as spatial partition structures  410  described below, may be used as the space-occupying units. However, it should be understood that the present invention is not limited thereto and any unit having an adjustable inner space, such as a balloon, may be used to adjust a cooling space (A) in the refrigeration trailer, as long as the unit can be placed in the trailer without being secured to the ceiling of the refrigeration trailer. 
     The space-occupying units to be described with reference to the drawings may be the spatial partition structures  410 , and the uncooling region (B) in the refrigeration trailer  20  is set by the spatial partition structures  410  disposed at the ceiling of the trailer and having an expandable inner space. 
     The fourth embodiment is different from the other embodiments in that vertical and horizontal bulkheads are not required, and in the fourth embodiment, the uncooling region (B) is set by expanding the inner space of the selected spatial partition structures  410  to a desired degree. 
     The refrigeration systems having a variable loading space according to the first to third embodiments of the invention are suitable for large trailers in which an elongated duct supplying cool air into a refrigeration trailer is provided at the ceiling thereof. In contrast, the refrigeration system having a variable loading space according to the fourth embodiment of the invention is more suitable for straight trucks having no duct at the ceiling thereof and may also be applied to large trailers. 
     In the fourth embodiment of the invention, as an example of the refrigerator vehicle, a straight truck will be described in which cool air is supplied into a trailer  20  through a hole at the front end thereof instead of a separate duct and a concave-convex pattern is not formed at the bottom thereof. 
     The spatial partition structures  410  are secured to the ceiling of the refrigeration trailer  20 . The spatial partition structures  410  may have the same width as the refrigeration trailer  20  and be arranged in a line along the longitudinal direction of the refrigeration trailer  20 . 
     In another example, the spatial partition structures  410  may have a smaller width than the refrigeration trailer  20  and be arranged at the ceiling of the refrigeration trailer  20  in the longitudinal and lateral directions. 
     As shown in  FIG. 34 , the spatial partition structures  410 , when not in use, are folded in the refrigeration trailer  20  in which loads (L) are loaded. In this case, the spatial partition structures  410  do not affect flow of cool air, and the cool air supplied from a refrigerator  21  may be supplied into the refrigeration trailer  20  as it is. 
       FIG. 35  is a view showing various operations of the loading space variable refrigeration system of a refrigerator vehicle according to the fourth embodiment of the present invention. 
     In  FIG. 35(a) , loads (L) are fully loaded at the bottom of the refrigeration trailer  20  and are lower in height than the ceiling of the refrigeration trailer  20 . In this case, the spatial partition structures  410  are expanded such that lower end portions thereof closely approach the upper surfaces of the loads (L). Therefore, as shown in  FIG. 35(a) , a space of the refrigeration trailer  20  to be cooled by cool air may be a space except for the spatial partition structures  410  expanded at the same level. 
     In  FIG. 35(b) , loads (L) are partially loaded at the bottom of the refrigeration trailer  20  and are lower in height than the ceiling of the refrigeration trailer  20 . In this case, some of the spatial partition structures  410  below which the loads (L) are present are expanded such that lower end portions thereof closely approach the upper surfaces of the loads (L). In addition, the rest of the spatial partition structures  410  below which the loads (L) are not present are expanded such that lower end portions thereof closely approach the bottom of the refrigeration trailer  20 . Therefore, as shown in  FIG. 35(b) , a space of the refrigeration trailer  20  to be cooled by cool air may be a space except for the spatial partition structures  410  expanded by different levels. Particularly, the spatial partition structure  410  deformed such that the lower end portion thereof closely approaches the bottom of the refrigeration trailer  20  blocks flow of the cool air, like the vertical bulkheads in the first to third embodiments of the invention. 
     The spatial partition structures  410  may be formed of a material to block air flow between the inside and outside thereof and expanded by simple user manipulation. 
     As shown in  FIG. 36 , for expansion or contraction, each of the spatial partition structures  410  may have side surfaces formed of a corrugated wall  411  that can be folded or unfolded. Therefore, when the spatial partition structure  410  is filled with air, the corrugated walls  411  are unfolded, thereby expanding the spatial partition structure  410 . In addition, when the air is discharged from the spatial partition structure  410  by folding the corrugated walls  411 , the spatial partition structure  410  is contracted. 
     In order to control the state of the corrugated walls  411 , the spatial partition structure  410  is provided at the upper portion thereof with an inner pulley  412 , and a wire  451  passing over the inner pulley  412  is secured at one end thereof to a lower wall  413  of the spatial partition structure  410  and at the other end thereof to a control key  454  via an outer pulley  453  outside the spatial partition structure  410 . 
     Therefore, as shown in  FIG. 36(a) , when an operator unwinds the wire  452  through the control key  454  before cool air is supplied into the refrigeration trailer  20 , the lower wall  413  of the spatial partition structure  410  is moved downwards and thus, the corrugated walls  411  are unfolded. In this way, the uncooling region (B) is set by the spatial partition structure  410 . In contrast, as shown in  FIG. 36(b) , when an operator pulls the wire  452  through the control key  454  once the refrigeration trailer  20  is completely cooled, the lower wall  413  of the spatial partition structure  410  is moved upwards and thus, the corrugated walls  411  are folded. In this way, the uncooling region (B) having been set by the spatial partition structure  410  is cancelled. 
     That is, tension of the wire may be controlled through the control key  454  by an operator, thereby adjusting the volume of the spatial partition structure  410 . 
     An opening  414  may be formed at the lower wall  413  of the spatial partition structure  410  such that the spatial partition structure  410  may be smoothly expanded and contracted. That is because, when the spatial partition structure  410  is completely sealed, a serious difference in air density occurs due to a temperature difference between the inside and outside of the spatial partition structure  410 , thereby causing serious deformation of the spatial partition structure  410 . Except for intense cold conditions, cool (heavy) air does not easily flow into the spatial partition structure  410  through the opening  414 , and therefore a setting effect of the uncooling region (B) through the spatial partition structure  410  is rarely reduced. 
     Embodiment 5 
       FIGS. 37 and 38  are views showing a loading space variable refrigeration system of a refrigerator vehicle according to a fifth embodiment of the present invention. 
     In practice, loads of different sizes are loaded in a refrigeration trailer  20 . In most cases, loads having different heights are loaded in the refrigeration trailer, instead of only one type of load, and therefore the heights of the loads (L) in the trailer are not uniform. If the horizontal bulkheads  110 ,  210 ,  310  according to the first to third embodiments of the invention are used in this case, the horizontal bulkheads are moved downwards only to the highest load (L), thereby allowing an unnecessary cooling space to be set together therein. 
     In this embodiment conceived to solve the problem, as shown in  FIGS. 37 and 38 , horizontal bulkheads  510  dividing an upper region in the refrigeration trailer  20  are configured to flexibly correspond to the shape in which loads (L) irregularly protrude upwards, instead of having the same height corresponding to the highest load. 
     As shown in  FIG. 37 , the plural horizontal bulkheads  510  are connected to one another and divide the upper region in the trailer. An uncooling region (B) in the refrigeration trailer  20  using the loading space variable refrigeration system of a refrigerator vehicle is set by the unit horizontal bulkheads  510  individually moving upwards and downwards and changing positions thereof and a vertical bulkhead  520  moving forwards and rearwards. 
     In the embodiment of  FIG. 37 , the unit horizontal bulkheads  510  may be individually moved upwards and downwards and freely perform position change (rotation). In the previous embodiments, the horizontal bulkheads  110 ,  210 ,  310  are moved downwards to the same height in the same position to fit the highest load (L). However, in this embodiment shown in  FIG. 37 , the uncooling region (B) may be set by the unit horizontal bulkheads  510  connected to one another, and the heights and positions of the unit horizontal bulkheads  510  are flexibly adjusted according to operator control to fit the heights of the loads (L) in the refrigeration trailer  20 . 
     As a result, it is possible to minimize an unnecessary cooling space, thereby further minimizing energy (heat or fuel) consumption for cooling. 
     In addition, as shown in  FIG. 38 , horizontal bulkheads  510  made of a flexible material are moved downwards to fit heights of loads (L) in a refrigeration trailer  20  and then partially deformed according to operator control, thereby optimally setting a cooling space (A). 
     Exemplary embodiments of the invention have been disclosed in the drawings and specification. The specific terms used herein are provided for the purpose of describing particular embodiments only and are not intended to limit the scope of the present invention disclosed in the claims. Accordingly, it should be understood by those skilled in the art that various modifications, changes, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be limited only by the accompanying claims and equivalents thereof.