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 2010-158753, 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 (also, called as 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. While the vehicle is driving, the fuel vapor trapped in the adsorbent canister is removed by flowing ambient air into the adsorbent canister, 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 a phase-change material 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 material 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 material. 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. 
     The binder is usually composed of a thermosetting resin such as phenol resin or acrylic resin. Because such thermosetting resin usually has low thermal conductivity, heat is hardly transferred between a center region and a surface region of the shaped heat storage material. Therefore, there has been need for improved shaped heat storage materials. 
     SUMMARY OF THE INVENTION 
     One aspect of this disclosure includes a shaped heat storage material having a heat-transfer member made from a high thermal conducting material and heat storage capsules that contains therein phase-change material capable of adsorbing and releasing heat depending on temperature alteration and are disposed around the heat-transfer member. 
     In accordance with this aspect, the heat-transfer member can improve heat conductivity in the shaped heat storage material. Thus, heat can be easily transferred between the center region and the surface region of the shaped heat storage material, so that it is able to effectively utilize latent heat of the phase-change material in the enter region of 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 in a first embodiment; 
         FIG. 2  is a partially cross-sectional schematic view showing a shaped heat storage material in the first embodiment; 
         FIG. 3  is a partially cross-sectional schematic view showing the shaped heat storage material in a second embodiment; and 
         FIG. 4  is a schematic view showing the shaped heat storage material in a third embodiment. 
     
    
    
     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. 
     A first embodiment of this disclosure will be described in reference to attached drawings. In this embodiment, an adsorbent canister (fuel vapor treating apparatus) containing shaped heat storage materials and attached to a vehicle such as automobile is shown. For convenience of explanation, directions (right, left, front and rear) are defined based on the adsorbent canister shown in  FIG. 1 . 
     As show in  FIG. 1 , an adsorbent canister  10  has a housing  12  made from resin materials. The housing  12  is composed of a housing 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 housing body  13 . An inner space of the housing 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 housing 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 housing 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 formed in, e.g., ball, cylinder, polygonal prism or concave polygonal prism shape. 
     As shown in  FIG. 2 , the shaped heat storage material  44  is made by shaping fine heat storage capsules  46  with a binder (not shown). The heat storage capsules  46  enclose phase-change materials capable of absorbing and releasing heat depending on temperature alteration therein. The heat storage capsules  46  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  46  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  46  and the binder into a continuous rod 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. 
     The shaped heat storage material  44  has a shaped body  45  composed of aggregated heat storage capsules  46  and a thin plate-shaped heat-transfer member  47  that is made from a high thermal conducting material and is disposed at a center region of the shaped body  45  ( FIG. 2 ). That is, a number of the heat storage capsules  46  are disposed around the heat-transfer member  47 . During manufacture of the shaped heat storage material  44 , the heat-transfer member  47  is positioned in the shaped body  45  by burying the heat-transfer member  47  in the center region of the shaped body  45 . The high thermal conducting material for the heat-transfer member  47  includes metal such as aluminum. 
     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  46  of the shaped heat storage material  44 . Thus, it is able to improve adsorption performance of the adsorbent  42  for the fuel vapor. 
     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  via the purge pipe  30 . Accordingly, ambient air is introduced 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 desrobed from the adsorbent  42  is prevented due to exotherm caused by phase change (from liquid phase to solid phase) of the phase-change material enclosed in the heat storage capsules  46  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  46  and then shaping the heat storage capsules  46  and the heat-transfer member  47  with the binder such that the heat storage capsules  46  are disposed around the heat-transfer member  47  made from the high thermal conducting material. Thus, the heat-transfer member  47  can improve heat-transfer efficiency in the shaped body  45  composed of the heat storage capsules  46 . Accordingly, it is able to effectively utilize latent heat of the phase-change material in the heat storage capsules  46 . 
     The heat-transfer member  47  extends from the center region to a surface region of the shaped body  45 , so that it is able to improve heat-transfer efficiency in the shaped body  45 . In detail, the heat-transfer member  47  can rapidly transfer heat between the center region and the surface region of the shaped body  45 . Although the number of the heat-transfer member  47  is one in this embodiment, the shaped body  45  can have a plurality of heat-transfer members  47 . 
     The heat-transfer member  47  is formed in a thin plate shape, so that it is able to increase contact area between the heat storage capsules  46  and the heat-transfer member  47 . The heat-transfer member  47  can be formed in other shape such as rod shape, granular shape, cylinder shape or hollow cylinder shape. In addition, the heat-transfer member  47  can be made from deformable material such that the heat-transfer member  47  can be deformed to fit the heat storage capsules  46  with the heat-transfer member  47 . 
     The high thermal conducting material of the heat-transfer member  47  is metal such as aluminum, aluminum alloy, copper or copper alloy. Various materials each having high thermal conductivity such as carbon fiber (e.g., carbon nanotube) can be used for the high thermal conducting material for the heat-transfer member  47 . 
     With respect to the adsorbent canister  10 , mixture of the shaped heat storage material  44  and the granular-shaped adsorbent  42  is filled in the housing  12 . Thus, because the shaped heat storage material  44  capable of effectively utilizing latent heat of the heat storage capsules  46  is mixed with the adsorbent  42  and filled in the housing  12 , it is able to improve desorption performance for the fuel vapor of the adsorbent  42 . 
     A second embodiment will be described. As shown in  FIG. 3 , a heat-transfer member  48  is formed in an optionally-branched fibrous shape in this embodiment. The heat-transfer member  48  is disposed in the shaped body  45  such that the heat-transfer member  48  extends from the center region to the surface region of the shaped body  45 . The shaped heat storage material  44  can be made by mixing the heat-storage member  48  and the heat storage capsules  46  with a binder and then shaping such mixture. Thus, the heat-storage member  48  is often exposed on the surface of the shaped body  45 . The heat-transfer member  48  is made from high thermal conducting materials. Preferably, the heat-transfer member  48  is made from metal materials such as aluminum, aluminum alloy, copper or copper alloy or carbon fiber materials such as carbon nanotube. 
     The heat-storage material  44  of this embodiment can have substantially same effect as those in the first embodiment. The heat-transfer member  48  is disposed in the shaped body  45  such that the heat-transfer member  48  continuously extends from the center region to the surface region of the shaped body  45 . Thus, the heat-transfer member  48  can rapidly transfer heat between the heat storage capsules  46  disposed in the surface region and the heat storage capsules  46  disposed in the center region. In addition, by filling mixture of the shaped heat storage material  44  and the adsorbent  42  into the adsorbent canister  10 , it is able to improve adsorption performance and desorption performance for the fuel vapor of the adsorbent  42 . 
     Because the heat-transfer member  48  is formed in fibrous shape, it is able to increase contact area between the heat-transfer member  48  and the heat storage capsules  46 . In addition, the heat-transfer member  48  can be easily deformed to fit the heat storage capsules  46 . A plurality of the heat-transfer members  48  can be disposed in the shaped body  45 . In a case that the shaped body  45  includes a plurality of the heat-transfer members  48 , although the heat-transfer members  48  preferably contact with each other, the heat-transfer members  48  can be disposed to avoid contact with each other. 
     A third embodiment will be described. As shown in  FIG. 4 , the shaped heat storage material  44  has a number of heat-transfer members  49  each formed in granular shape or powder shape. The heat-transfer members  49  are distributed throughout the whole of the shaped body  45 . The shaped heat storage material  44  can be made by mixing a number of the heat storage capsules  46  and the heat-transfer members  49  with a binder and then shaping such mixture. The heat-transfer members  49  are made from a high thermal conducting material. Preferably, the heat-transfer members  49  are made from metal materials such as aluminum, aluminum alloy, copper or copper alloy. In addition, carbon fibers can be used for the heat-transfer members  49 , e.g., by shaping carbon fibers into granular shape. 
     The shaped heat-storage material  44  of this embodiment can have substantially same effect as those in the first embodiment. In addition, because the heat-transfer members  49  are distributed throughout the whole of the shaped body, it is able to improve heat conductivity between the center region and the surface region of the shaped body  45 . 
     Each of the heat-transfer members  49  is formed in granular shape or powder shape. Thus, the heat-transfer members  49  can be easily mixed with the heat storage capsules  46 , so that it is able to improve formability of the shaped heat storage material  44 . 
     The shaped heat storage material  44  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. In addition, it is able to shape the heat-transfer members in various shapes other than those described above, for example, C-shape, H-shape, L-shape, X-shape, lattice shape or combination thereof.