Abstract:
A shaped heat storage material has a shaped body composed of a binder and heat storage capsules containing a heat storage material therein. And, the shaped body has at least one of a projection, a depressed portion and a hollow structure defining a hollow space therein.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to Japanese patent application serial number 2010-155445, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This disclosure relates to heat storage materials used for treatment of vaporized fuel and adsorbent canisters containing such heat storage material. 
     2. Description of the Related Art 
     A vehicle such as gasoline vehicle has an adsorbent canister (fuel vapor treating apparatus) filled with an adsorbent capable of adsorbing and desorbing fuel vapor vaporized in a fuel tank in order to prevent the fuel vapor from flowing outside of the vehicle. The adsorbent canister temporarily traps the fuel vapor while the vehicle is parked. The fuel vapor trapped in the adsorbent canister is removed by flowing ambient air into the adsorbent canister while the vehicle is driving, and then the fuel vapor mixed with the ambient air is burned in an internal combustion engine of the vehicle. In a case that the adsorbent is composed of activated carbon or the like, as the temperature of the adsorbent becomes higher, the adsorbent has lower adsorption capacity. Thus, when the fuel vapor adsorbs onto the adsorbent, the temperature of the adsorbent increases due to exotherm caused by adsorption of the fuel vapor, so that adsorption ability of the adsorbent decreases. On the contrary, when the fuel vapor desorbs from the adsorbent, the temperature of the adsorbent decreases due to endotherm caused by desorption of the fuel vapor, so that desorption ability of the adsorbent decreases. 
     Japanese Laid-Open Patent Publication No. 2005-233106 discloses an adsorbent canister filled with a granulated adsorbent and a shaped heat storage material. The shaped heat storage material is made by enclosing phase-change materials capable of absorbing and releasing heat depending on its liquid-solid phase change into micro capsules and shaping the micro capsules with a binder into ball shape, cylinder shape, polygonal shape or the like. Accordingly, when the fuel vapor adsorbs onto the adsorbent, increase in temperature of the adsorbent can be suppressed due to endotherm caused by melting of the phase-change materials in the microcapsules, whereas when the fuel vapor desorbs from the adsorbent, decrease in temperature of the adsorbent can be suppressed due to exotherm caused by solidification of the phase-change materials. Therefore, temperature alteration of the adsorbent caused by adsorption and desorption of the fuel vapor can be prevented, so that it is able to improve adsorption performance and desorption performance of the adsorbent. 
     As void ratio of mixture of the adsorbent and the heat storage material filled in the adsorbent canister is higher, the adsorbent canister can more effectively prevent the fuel vapor from flowing into the atmosphere. Thus, there has been a need for improved shaped heat storage material. 
     SUMMARY OF THE INVENTION 
     One aspect of this disclosure includes a shaped heat storage material having a shaped body composed of a binder and heat storage capsules containing a heat storage material therein. The shaped body has at least one of a projection, a depressed portion and a hollow structure defining a hollow space therein. 
     In accordance with this aspect, the inner hollow space, the projection or the depressed portion can keep a void space, so that it is able to increase void ratio of the shaped heat storage material. Thus, when using this shaped heat storage material with an adsorbent for an adsorbent canister, it is able to increase void ratio of mixture of the adsorbent and the shaped heat storage material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a schematic cross-sectional view of an adsorbent canister connected to a fuel tank and to an internal combustion engine; 
         FIG. 2  is a perspective view of a shaped heat storage material; 
         FIG. 3  is a perspective view of a first variant of the shaped heat storage material; 
         FIG. 4  is a perspective view of a second variant of the shaped heat storage material; 
         FIG. 5  is a perspective view of a third variant of the shaped heat storage material; 
         FIG. 6  is a partial cross-sectional perspective view of a fourth variant of the shaped heat storage material; 
         FIG. 7  is a perspective view of a fifth variant of the shaped heat storage material; 
         FIG. 8  is a perspective view of a sixth variant of the shaped heat storage material; 
         FIG. 9  is a perspective view of a seventh variant of the shaped heat storage material; 
         FIG. 10  is a perspective view of an eighth variant of the shaped heat storage material; 
         FIG. 11  is a perspective view of a ninth variant of the shaped heat storage material; 
         FIG. 12  is a perspective view of a tenth variant of the shaped heat storage material; 
         FIG. 13  is a perspective view of an eleventh variant of the shaped heat storage material; and 
         FIG. 14  is a perspective view of a twelfth variant of the shaped heat storage material. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Each of the additional features and teachings disclosed above and below may be utilized separately or in conjunction with other features and teachings to provide improved heat storage materials. Representative examples, which examples utilize many of these additional features and teachings both separately and in conjunction with one another, will now be described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Moreover, various features of the representative examples and the dependent claims may be combined in ways that are not specifically enumerated in order to provide additional useful embodiments of the present teachings. 
     An embodiment of this disclosure will be described in reference to the attached drawings. An adsorbent canister containing a shaped heat storage material and mounted on a vehicle will be shown.  FIG. 1  is a schematic cross-sectional view of the adsorbent canister connected to a fuel tank and an internal combustion engine. For convenience of explanation, directions (i.e., right, left, front and rear) are defined based on  FIG. 1 . 
     As show in  FIG. 1 , an adsorbent canister  10  has a case  12  made from resin materials. 
     The case  12  is composed of a case body  13  formed in a hollow cylinder shape with a closed front end (upper end in  FIG. 1 ) and an open rear end (lower end in  FIG. 1 ) and a cover  14  configured to close the rear end of the case body  13 . An inner space of the case body  13  is divided into a main chamber  17  at a left side and an auxiliary chamber  18  at a right side by a partition wall  15 . A communication chamber  20  is defined at a rear section of the case body  13  near the cover  14  such that the main chamber  17  and the auxiliary chamber  18  are fluidly connected with each other via the communication chamber  20 . 
     The case body  13  has on its front surface (an upper surface in  FIG. 1 ) a vapor introducing port  22  and an exhaust port  23  each fluidly connecting with the main chamber  17  and an air communicating port  24  fluidly communicating with the auxiliary chamber  18 . The vapor introducing port  22  is connected with a fuel tank  27  (in detail, an upper section of the fuel tank  27  where gases are reserved) via a vapor pipe  26 . The exhaust port  23  is connected to an air intake pipe  32  for an internal combustion engine  31  via a purge pipe  30 . The air intake pipe  32  is provided with a throttle valve  33  for controlling intake airflow. The purge pipe  30  is connected to the air intake pipe  32  downstream of the throttle valve  33  (i.e., between the internal combustion engine  31  and the throttle valve  33 ). The purge pipe  30  is provided with a purge valve  34 . The air communicating port  24  is open to the atmosphere. 
     The main chamber  17  is equipped with a front filter  36  at a front end and a rear filter  37  at a rear end. The auxiliary chamber  18  is also equipped with a front filter  36  and a rear filter  37  in a same manner. Each of the filters  36  and  37  is made of a resin-based non-woven cloth, urethane foam or the like. In the main chamber  17  and the auxiliary chamber  18 , porous plates  38  are disposed along a rear surface of each rear filter  37 . In addition, spring members  40  each composed of a coil spring are disposed between the porous plates  38  and the cover  14 . 
     In the main chamber  17  and the auxiliary chamber  18 , a mixture of a granular-shaped adsorbent  42  and a granular-shaped heat storage material  44  is filled between the front filters  36  and the rear filters  37 . The adsorbent  42  can be made from known materials suitable for adsorbent, so that such materials will not be described in detail. For example, the adsorbent  42  can be made of granulates of activated carbon. In addition, the granulates of activated carbon can include, for example, granular activated carbon (crushed activated carbon) and extruded activated carbon formed by shaping powdered activated carbon with a binder. The adsorbent  42  can be shaped in, e.g., ball, cylinder, polygonal prism and concave polygonal prism. 
     The shaped heat storage material  44  are made by enclosing phase-change materials capable of absorbing and releasing heat depending on temperature alteration into micro capsules in order to make heat storage capsules and then shaping the heat storage capsules with a binder. The heat storage capsules can be made from known materials suitable for the heat storage capsule such as those disclosed in Japanese Laid-Open Patent Publication No. 2005-233106, so that the heat storage capsules will not be described in detail. Although various materials can be used for the binder, thermosetting resin such as phenol resin or acrylic resin is preferable in light of strength and stability against temperature required for the adsorbent canister  10  and solvent. The shaped heat storage material  44  and the adsorbent  42  preferably have 0.1-1.5 g/cc of density, respectively. A ratio of the shaped heat storage material  44  to total amount of mixture of the adsorbent  42  and the shaped heat storage material  44  is preferably 5-40% by weight. The shaped heat storage material  44  can be shaped in accordance with known methods such as those disclosed in Japanese Laid-Open Patent Publication No. 2005-233106. For example, the shaped heat storage material  44  can be easily shaped by extruding mixture containing the heat storage capsules and the binders into an elongated cylinder shape and then cutting such extruded product in a predetermined length. Thus, the shaped heat storage material  44  is basically formed in a prism-like shape such as cylinder shape, polygonal prism or the like. 
     As shown in  FIG. 2 , the shaped heat storage material  44  is formed in a hollow cylinder shape. That is, the shaped heat storage material  44  is composed of a shaped body  45  formed in a hollow cylinder shape. The shaped body  45  has a hollow cylinder portion  48  and defines a hollow space  47  that is composed of a through-hole  46  penetrating the shaped body  45  in an axial direction. The shaped heat storage material  44  can be formed in other hollow prism-like shape such as square prism. 
     Next, operation of a fuel vapor treating system including the adsorbent canister  10  will be described ( FIG. 1 ). The fuel vapor treating system is composed of the adsorbent canister  10 , the vapor pipe  26 , the fuel tank  27 , the purge pipe  30 , the air intake pipe  32  and purge valve  34 , etc. When the internal combustion engine  31  is stopped, the fuel vapor, e.g., vaporized in the fuel tank  27  flows into the main chamber  17  via the vapor pipe  26 . Then, most of the fuel vapor adsorbs onto the adsorbent  42  filled in the main chamber  17 . Remaining fuel vapor that has not adsorbed onto the adsorbent  42  in the main chamber  17  flows into the auxiliary chamber  18  via the communication chamber  20  and then adsorbs onto the adsorbent  42  filled in the auxiliary chamber  18 . In this state, increase in temperature of the adsorbent  42  caused by exothermal reaction where the fuel vapor adsorbs onto the adsorbent  42  can be suppressed by endotherm caused by phase change (from solid phase to liquid phase) of the phase-change material in the heat storage capsules of the shaped heat storage material  44 . Thus, it is able to improve adsorption performance of the adsorbent  42  for the fuel vapor. 
     On the other hand, in a state that the internal combustion engine  31  is running, when the purge valve  34  is opened, negative pressure in the internal combustion engine  31  can act on the adsorbent canister  10 . Due to this action, ambient air flows into the auxiliary chamber  18  via the air communicating port  24 . The air introduced into the auxiliary chamber  18  desorbs the fuel vapor from the adsorbent  42  filled in the auxiliary chamber  18 . And then, the air flows into the main chamber  17  via the communication chamber  20  and desorbs the fuel vapor from the adsorbent  42  filled in the main chamber  17 . In this state, decrease in temperature of the adsorbent  42  caused by endothermal reaction where the fuel vapor is desorbed from the adsorbent  42  is prevented due to exotherm caused by phase change (from liquid phase to solid phase) of the phase-change materials enclosed in the heat storage capsules of the shaped heat storage material  44 . Thus, it is able to improve desorption performance where the fuel vapor is desorbed from the adsorbent  42 . The air mixed with the fuel vapor that has been desorbed from the adsorbent  42  is discharged (i.e., purged) into the air intake pipe  32  via the purge pipe  30  and then is burned in the internal combustion engine  31 . 
     The shaped heat storage material  44  ( FIG. 2 ) used for the adsorbent canister  10  ( FIG. 1 ) is made by enclosing phase-change materials capable of absorbing and releasing heat depending on temperature alteration into microcapsules in order to make fine heat storage capsules and shaping the heat storage capsules with the binder. The shaped heat storage material  44  is composed of the shaped body  45  having the hollow space  47 . The hollow space  47  of the shaped body  45  increases void space, thereby increasing void, ratio of the shaped heat storage material  44 . 
     The hollow space  47  is composed of the through-hole  46  passing through the shaped body  45 . Thus, the hollow space  47  can improve ventilation of the shaped heat storage material  44 . 
     The adsorbent canister  10  is filled with a mixture of the shaped heat storage material  44  and the adsorbent  42 . Thus, it is able to increase void ratio of such mixture of the shaped heat storage material  44  and the adsorbent  42  by using the shaped heat storage material  44  having larger void ratio. Thus, it is able to decrease diffusive density of the fuel vapor remaining in the adsorbent canister  10  while the vehicle is parked and thus to reduce the amount of the fuel vapor flowing into the atmosphere. In addition, the hollow space  47  improves ventilation of the shaped heat storage material  44 , so that it is able to decrease pressure loss in the adsorbent canister  10  filled with the mixture of the shaped heat storage material  44  and the adsorbent  42  in order to make refueling easier. 
     Next, variants of the shaped heat storage material  44  will be described.  FIG. 3  shows a first variant of the shaped heat storage material  44 . As shown in  FIG. 3 , the first variant of the shaped heat storage material  44  is composed of the hollow cylinder portion  48  further having a partition  50  extending in the axial direction and dividing the hollow space  47  into two spaces  51  that pass through the shaped body  45 . Thus, the partition  50  increases structural strength of the shaped heat storage material  44 . 
       FIG. 4  shows a second variant of the shaped heat storage material. As shown in  FIG. 4 , the second variant of the shaped heat storage material  44  is composed of the hollow cylinder portion  48  further having a honeycomb-shaped partition  53  dividing the hollow space  47  into many spaces  54 . The spaces  54  extend in the axial direction and pass through the shaped body  45 . Thus, the partition  53  increases structural strength of the shaped heat storage material  44 . 
       FIG. 5  shows a third variant of the shaped heat storage material. As shown in  FIG. 5 , the third variant of the shaped heat storage material  44  is composed of the hollow cylinder portion  48  further having a slit  56  extending in the axial direction and passing through the hollow cylinder portion  48  in the radial direction. The slit  56  increases void ratio of the shaped heat storage material  44 . 
       FIG. 6  shows a fourth variant of the shaped heat storage material. As shown in  FIG. 6 , the fourth, variant of the shaped heat storage material  44  is composed of the hollow cylinder portion  48  further having a closed end (right end in  FIG. 6 ) that is closed with a blocking portion  58 . The blocking portion  58  increases structural strength of the shaped heat storage material  44 . 
       FIG. 7  shows a fifth variant of the shaped heat storage material. As shown in  FIG. 7 , the fifth variant of the shaped heat storage material  60  is formed in a star prism shape having a star shaped cross-section. That is, the shaped heat storage material  60  is composed of a shaped body  61  formed in a pentagonal prism shape and five triangular prisms  62  extending along side surfaces of the shaped body  61  in the axial direction. Thus, the triangular prisms  62  make void spaces  63  between the triangular prisms  62  and thus increase the void ratio of the shaped heat storage material  60 . 
       FIG. 8  shows a sixth variant of the shaped heat storage material. As shown in  FIG. 8 , the sixth variant of the shaped heat storage material  60  is composed of the shaped body  61  further having a through-hole  65  passing through the shaped body  61  in the axial direction. The through-hole  65  forms a hollow space  66  and thus increases the void ratio of the shaped heat storage material  60 . 
       FIG. 9  shows a seventh variant of the shaped heat storage material. As shown in  FIG. 9 , the seventh variant of the shaped heat storage material  68  is formed in a crisscross prism shape. That is, the shaped heat storage material  68  is composed of a shaped body  69  having a square prism shape and four square prisms  70  extending along side surfaces of the shaped body  69  in the axial direction. Because the shaped heat storage material  68  has a rectangular cross-section, the square prisms  70 (A) having a wider side surface and the square prisms  70 (B) having a narrow side surface are alternately positioned around the shaped body  69  in the circumference direction. The square prisms  70 (A) and  70 (B) make void spaces  71  between the square prisms  70 (A) and  70 (B), and thus increase void ratio of the shaped heat storage material  68 . 
       FIG. 10  shows an eighth variant of the shaped heat storage material. As shown in  FIG. 10 , the eighth variant of the shaped heat storage material  73  is formed in a threaded shaft shape. That is, the shaped heat storage material  73  is composed of a shaped body  74  having a circular cylinder shape and a projected rim  75  that is formed in a screw thread shape and projects from an outer circumference surface of the shaped body  74 . Thus, the projected rim  75  provided to the shaped body  74  keeps void spaces  76 , and thus increases the void ratio of the shaped heat storage material  73 . 
       FIG. 11  shows a ninth variant of the shaped heat storage material. As shown in  FIG. 11 , the ninth variant of the shaped heat storage material  78  is composed of a shaped body  79  formed in a porous cylinder shape having many fine pores  80 . Thus, the pores  80  of the shaped body  79  increase the void ratio of the heat storage material  78 . 
       FIG. 12  shows a tenth variant of the shaped heat storage material. As shown in  FIG. 12 , the tenth variant of the shaped heat storage material  78  is composed of the shaped body  79  further having a through-hole  82  passing through the shaped body  79  in the axial direction. The through-hole  82  makes a hollow space  83 , and thus increases the void ratio of the shaped heat storage material  78 . 
       FIG. 13  shows an eleventh variant of the shaped heat storage material. As shown in  FIG. 13 , the eleventh variant of the shaped heat storage material  85  is composed of a shaped body  86  having many depressed portions  87  formed on a surface (both end surfaces and an outer circumference surface) of the shaped body  86 . The depressed portions  87  increase the void ratio of the shaped heat storage material  85 . 
       FIG. 14  shows a twelfth variant of the shaped heat storage material. As shown in  FIG. 14 , the twelfth variant of the shaped heat storage material  90  is composed of a shaped body  91  basically formed in a ball shape and many conical projections  92  protruding from a surface of the shaped body  91 . The projections  92  can keep spaces  93 , and thus increase the void ratio of the shaped heat storage material  90 . 
     The shaped heat storage material of this disclosure can applied to other apparatuses each requiring a heat storage ability, e.g., for coolant water used for the internal combustion engine, engine oil, transmission oil, or air for air conditioner. In the described embodiment, although the fuel vapor desorbed from the adsorbent is flowed into the air intake pipe, the fuel vapor desorbed from the adsorbent can be flowed into another device (for example, a recovery apparatus for condensing the fuel vapor) due to action of a suction pump.