Patent Publication Number: US-9427714-B2

Title: Mixer drum apparatus having blades and inlet seal

Description:
RELATED APPLICATIONS 
     The present application is a National Phase of International Application Number PCT/JP2012/070169, filed Aug. 8, 2012, and claims priority from Japanese Application Number 2011-257640 Nov. 25, 2011. 
     TECHNICAL FIELD 
     The present invention relates to a mixer drum apparatus to stir material to be stored such as ready-mixed concrete. 
     BACKGROUND ART 
     JP8-40136A discloses a mixer drum apparatus mounted on a concrete mixer truck. This mixer drum apparatus includes a rotating drum, a hopper that directs charged ready-mixed concrete to the drum, an inlet seal that is provided at an opening end of the drum and is connected to the hopper, and a pair of blades that spirally extend from the opening end of the drum to the front side of the concrete mixer truck (back side of the drum). 
     The inlet seal has an inlet seal pipe that is connected to an outlet of the hopper, and a pair of inlet seal panels that extend from the inlet seal pipe to the back side of the drum to be connected to inner peripheries of the blades. 
     When charging the ready-mixed concrete, the inlet seal pipe directs the ready-mixed concrete that is charged to the hopper to the back side of the drum. 
     At the time of stirring or mixing with the ready-mixed concrete being loaded closer to a maximum load, the inlet seal panels receive the ready-mixed concrete that is over the inner peripheries of the blades in the vicinity of the opening end of the drum, thereby preventing the ready-mixed concrete from being discharged from the opening end of the drum. 
     SUMMARY OF THE INVENTION 
     According to the above-described conventional mixer drum apparatus, however, the inlet seal panels are provided over the inner peripheries of the pair of blades that are arranged in a front-to-rear direction in the vicinity of the opening end of the drum, and space between the blades arranged in the front-to-rear direction is covered by the inlet seal panels like a tunnel. This makes it likely that the ready-mixed concrete adheres between the pair of blades, and makes it difficult to clean the ready-mixed concrete adhered between the blades, at the time of cleaning inside the drum. 
     It is an object of the present invention to provide a mixer drum apparatus in which material to be stored, such as ready-mixed concrete, is less likely to adhere between blades, and is capable of improving cleaning performance. 
     According to one aspect of the present invention, a mixer drum apparatus to stir material to be stored is provided which comprises a freely-rotatable drum having an opening end opened at one end to receive the material to be stored therein; a plurality of spirally-shaped blades provided inside the drum to have a phase difference; and an inlet seal provided at the opening end of the drum and connected partially to the blades, wherein the inlet seal located between the blades forms an opening causing the material to be stored to pass through. 
     Embodiments of the present invention and advantages thereof are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view showing a concrete mixer truck according to a first embodiment; 
         FIG. 2  is a cross-sectional view of a drum; 
         FIG. 3  is a perspective view of the drum viewed from a diagonally rear right direction; 
         FIG. 4  is a perspective view of the drum viewed from a diagonally rear left direction; 
         FIG. 5  is an expanded view of an inlet seal; 
         FIG. 6  is a perspective view of the inlet seal; 
         FIG. 7  is a perspective view of the drum according to a second embodiment viewed from a diagonally rear left direction; 
         FIG. 8  is a cross-sectional view of the drum; 
         FIG. 9  is an expanded view of the inlet seal; 
         FIG. 10  is a perspective view of the inlet seal; 
         FIG. 11  is a perspective view of the inlet seal according to a third embodiment. 
     
    
    
     EMBODIMENTS OF THE INVENTION 
     A first embodiment will be explained with reference to  FIG. 1  to  FIG. 6 . 
       FIG. 1  is a side view showing schematic structure of a concrete mixer truck  1 . The concrete mixer truck  1  for loading ready-mixed concrete is equipped with a mixer drum apparatus  9  to stir the ready-mixed concrete on a vehicle body  2 . 
     The mixer drum apparatus  9  includes supporting units  3  and  4  that are provided in the front and in the rear of the vehicle body  2 , a drum  10  that is supported by the supporting units  3  and  4  freely-rotatable around a rotation center axis O, and a not-shown driving unit that transmits power of an engine to the drum  10 . The mixer drum apparatus  9  drives the drum  10  to rotate in both normal and reverse rotation directions. 
     The hollow spindle-shaped drum  10  has a cylindrical portion  17  that is provided at the center thereof, a front conical portion  16  that reduces its diameter from the cylindrical portion  17  to the front of the concrete mixer truck (left side in  FIG. 1 ), and a rear conical portion  18  that reduces its diameter from the cylindrical portion  17  to the rear of the concrete mixer truck (right side in  FIG. 1 ). 
     In the rear of the drum  10 , an opening end  11  for charging and discharging the ready-mixed concrete (charging and discharging port) is provided. The drum  10  is arranged in such a manner that its rotation center axis O is tilted relative to a horizontal line. Therefore, the opening end  11  of the drum  10  opens diagonally upward. 
     A hopper  5  for charging the ready-mixed concrete is provided in the upper rear of the opening end  11  of the drum  10 . An inlet seal  40  is provided inside the opening end  11  of the drum  10 . The ready-mixed concrete charged to the hopper  5  is guided by the inlet seal  40  from the opening end  11  of the drum  10  into the drum  10 . 
     A scoop  6  and a chute  7  are provided in the lower rear of the opening end  11  of the drum  10 . The ready-mixed concrete discharged from the opening end  11  is guided by the scoop  6  to the chute  7 , and discharged by the chute  7  in a predetermined direction. 
     Inside the drum  10 , a first blade  20  and a second blade  30 , each of which has a belt shape and projects from an inner wall  12  to extend spirally, are provided. A pair of first blade  20  and second blade  30 , each extending in the spiral belt shape, has a phase difference of 180° to each other about the rotation center axis O. 
     The first blade  20  has a spiral-shaped outer periphery (base end)  25  that is connected to the inner wall  12  of the drum  10 , and a spiral-shaped inner periphery (tip end)  24  that is extended from the outer periphery  25  toward the inside of the drum  10 . Similarly, the second blade  30  has a spiral-shaped outer periphery (base end)  35  that is connected to the inner wall  12  of the drum  10 , and a spiral-shaped inner periphery (tip end)  34  that is extended from the outer periphery  35  toward the inside of the drum  10 . 
     At the time of charging, stirring and mixing the ready-mixed concrete to and in the drum  10 , the drum  10  is driven to rotate normally and rotated in a counterclockwise direction viewed from the rear (right end side in  FIG. 1 ). The ready-mixed concrete in the drum  10  is transferred from the rear to the front of the drum  10  (from the right to the left in  FIG. 1 ) by the rotating first blade  20  and second blade  30 . Thus, the ready-mixed concrete is stirred and mixed and its solidification is prevented. 
     At the time of discharging the ready-mixed concrete from the drum  10 , the drum  10  is driven to rotate reversely and rotated in a clockwise direction viewed from the rear. The ready-mixed concrete in the drum  10  is transferred from the front to the rear of the drum  10  by the rotating first blade  20  and second blade  30  and discharged from the opening end  11  of the drum  10 . 
     In  FIG. 2 , the first blade  20  is illustrated by broken lines and the second blade  30  is illustrated by solid lines. The first blade  20  in the spiral belt shape has a tapered first blade tip end portion  21  that extends to the vicinity of the opening end  11  of the drum  10 , and the second blade  30  in the spiral belt shape has a tapered second blade tip end portion  31  that extends to the vicinity of the opening end  11  of the drum  10 . The first blade tip end portion  21  and the second blade tip end portion  31  reduce in height with respect to the inner wall  12  of the drum  10  gradually from the front side (back side) of the drum  10  toward the opening end  11 . 
     As shown in  FIG. 3  and  FIG. 4 , a pair of auxiliary blades  29  and  39  that extend from the inner wall  12  is provided in the vicinity of the opening end  11  of the drum  10 . The auxiliary blades  29  and  39  are arranged to have a phase difference of 180° with respect to each other and to have a predetermined phase difference with respect to the first blade tip end portion  21  and the second blade tip end portion  31 , respectively. 
     When the drum  10  is rotated reversely to discharge the ready-mixed concrete, the ready-mixed concrete is transferred to the vicinity of the opening end  11  of the drum  10  by the first blade  20  and the second blade  30 , and pushed out from the opening end  11  of the drum  10  to the scoop  6  by the tapered first blade tip end portion  21  and second blade tip end portion  31  and the auxiliary blades  29  and  39 . 
     Hereinafter, structure of the inlet seal  40  will be explained.  FIG. 5  is an expanded view of the inlet seal  40 , and  FIG. 6  is a perspective view of the inlet seal  40 . The inlet seal  40  has an inlet seal pipe  41  having an annular shape, and a first inlet seal panel  42  and a second inlet seal panel  43  each extending in a curved triangular plate shape from the inlet seal pipe  41 . 
     The inlet seal pipe  41  is formed to have the annular shape around the rotation center axis O. An outlet (not shown) of the hopper  5  is connected to an opening end of the inlet seal pipe  41 . An inlet space  28  defined inside the inlet seal pipe  41  communicates with the hopper  5  to introduce the ready-mixed concrete. 
     When the drum  10  rotates normally to charge the ready-mixed concrete, the ready-mixed concrete charged to the hopper  5  is guided by the inlet seal pipe  41  to the front side (back side) of the drum  10  over the first blade tip end portion  21  and the second blade tip end portion  31 . 
     The first inlet seal panel  42  and the second inlet seal panel  43  are arranged to have a phase difference of 180° to each other about the rotation center axis O. Each of the first inlet seal panel  42  and the second inlet seal panel  43  is formed to have the curved triangular plate shape extending to connect the front end of the inlet seal pipe  41  and the inner peripheries  24  and  34  of the first blade  20  and the second blade  30 , respectively. 
     The inlet seal pipe  41 , the first inlet seal panel  42  and the second inlet seal panel  43  are separately formed by a metal plate and connected to each other by welding and the like. Incidentally, the inlet seal pipe  41 , the first inlet seal panel  42  and the second inlet seal panel  43  may be formed as one unit. 
     When the drum  10  is rotated normally to stir or mix the ready-mixed concrete, with the ready-mixed concrete being loaded closer to a maximum load, the ready-mixed concrete that is over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  gets onto the first inlet seal panel  42  and the second inlet seal panel  43 , in the vicinity of the opening end  11  of the drum  10 . This makes it possible to prevent the ready-mixed concrete from being discharged from the opening end  11  of the drum  10  to the scoop  6 . 
     Incidentally, according to a conventional concrete mixer truck, inlet seal panels  142  and  143  of the inlet seal are formed in a conical shape (tapered cylindrical shape) that increases its diameter along the rear conical portion of the drum, and the pair of blades arranged in the front-to-rear direction in the vicinity of the opening end of the drum is formed to have approximately the same extension height, as shown by two-dotted chain lines in  FIG. 2 . Therefore, it was necessary to provide the inlet seal panels  142  and  143  over a wide area in the vicinity of the opening end of the drum, in order to prevent the ready-mixed concrete from getting over the blades and being discharged. As a result, space between the blades arranged in the front-to-rear direction is covered by the inlet seal panels  142  and  143  like a tunnel, which makes it likely that the ready-mixed concrete adheres between the blades, and makes it difficult to clean the ready-mixed concrete adhered between the blades at the time of cleaning the concrete mixer truck. 
     For this reason, the inlet seal  40  of this embodiment is structured to make the space open between the first blade  20  and the second blade  30  that are arranged in the direction of the rotation center axis O of the drum  10 , and not to cover the space between the first blade  20  and the second blade  30  like a tunnel. 
     Each of regions A and B, as shown in  FIG. 4  and  FIG. 5 , is set to have an angular range of 180° about the rotation center axis O, with a center line Z at the end of the drum forming a border therebetween. In the region A, the first blade tip end portion  21  exists as a portion of the first blade  20  separated from the inlet seal pipe  41 . In the region B, the second blade tip end portion  31  exists as a portion of the second blade  30  separated from the inlet seal pipe  41 . 
     An annular outlet space  27  is defined between the inlet seal pipe  41  and the opening end  11  of the drum  10 . The outlet space  27  opens toward the outside of the drum  10  as the first blade tip end portion  21  and the second blade tip end portion  31  are separated from the inlet seal pipe  41  in the regions A and B. 
     The first inlet seal panel  42  is arranged in the region A so as not to cover the space between the first blade  20  and the second blade  30  like a tunnel. The second inlet seal panel  43  is arranged in the region B so as not to cover the space between the first blade  20  and the second blade  30  like a tunnel. 
     A first opening  26  is defined in the region B by a first seal side portion  42   a  of the first inlet seal panel  42 , to make the space open between the first blade  20  and the second blade  30  (refer to  FIG. 3  and  FIG. 4 ). 
     A second opening  36  is defined in the region A by a second seal side portion  43   a  of the second inlet seal panel  43 , to make the space open between the first blade  20  and the second blade  30  (refer to  FIG. 3  and  FIG. 4 ). 
     Thereby, the space between the first blade  20  and the second blade  30  that are arranged in the front-to-rear direction is not covered by the first inlet seal panel  42  and the second inlet seal panel  43  like a tunnel. This makes it difficult for the ready-mixed concrete to adhere between the first blade  20  and the second blade  30 , and makes it easy to clean the space between the first blade  20  and the second blade  30  at the time of cleaning inside the drum  10 . 
     The inlet seal pipe  41  has a first blade connecting portion  24   a  and a second blade connecting portion  34   a  that are connected to the inner peripheries (tip ends)  24  and  34  of the first blade  20  and the second blade  30 . 
     The first inlet seal panel  42  has a front side seal end portion (front end portion)  42   b  that extends from the inlet seal pipe  41  to the back side (front) of the drum  10  to be connected to the inner periphery  34  of the second blade  30 . 
     Similarly, the second inlet seal panel  43  has a front side seal end portion (front end portion)  43   b  that extends from the inlet seal pipe  41  to the back side (front) of the drum  10  to be connected to the inner periphery  24  of the first blade  20 . 
     The center line Z at the end of the drum is a line orthogonal to the rotation center axis O of the drum  10 . The first inlet seal panel  42  has the first seal side portion  42   a  that touches the center line Z at the end of the drum and extends in approximately parallel to the rotation center axis O of the drum  10 . The second inlet seal panel  43  has the second seal side portion  43   a  that touches the center line Z at the end of the drum and extends in approximately parallel to the rotation center axis O of the drum  10 . 
     The expanded view in  FIG. 5  shows the first inlet seal panel  42  and the second inlet seal panel  43  according to this embodiment in solid lines. Supposing that the lines extending from the inlet seal pipe  41  in approximately parallel to the rotation center axis O of the drum  10  are reference lines L 1  and L 2 , the first seal side portion  42   a  and the second seal side portion  43   a  are formed to extend along the reference lines L 1  and L 2  in an approximately linear manner. 
     The first inlet seal panel  42  is formed in the curved triangular plate shape that extends to connect the first seal side portion  42   a , a front end  41   a  of the inlet seal pipe  41 , and the inner periphery  34  of the second blade  30 . The second blade connecting portion  34   a  becomes a sharply-angled tip end (vertex) of the first inlet seal panel  42 . The first seal side portion  42   a  is offset with respect to the second blade connecting portion  34   a  toward the second blade tip end portion  31  (refer to  FIG. 5 ). This makes it possible to prevent the first inlet seal panel  42  from blocking the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction. It should be noted that the first seal side portion  42   a  may be connected to the second blade connecting portion  34   a.    
     Similarly, the second inlet seal panel  43  is formed in the curved triangular plate shape that extends to connect the second seal side portion  43   a , the front end  41   a  of the inlet seal pipe  41 , and the inner periphery  24  of the first blade  20 . The first blade connecting portion  24   a  becomes a sharply-angled tip end (vertex) of the second inlet seal panel  43 . The second seal side portion  43   a  is offset with respect to the first blade connecting portion  24   a  toward the first blade tip end portion  21  (refer to  FIG. 5 ). This makes it possible to prevent the second inlet seal panel  43  from blocking the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction. It should be noted that the second seal side portion  43   a  may be connected to the first blade connecting portion  24   a.    
     As the first inlet seal panel  42  and the second inlet seal panel  43  are not provided in the first opening  26  and the second opening  36 , the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction is opened. 
     The first opening  26  is defined spirally among the first seal side portion  42   a  of the first inlet seal panel  42 , the inner periphery  24  of the first blade  20 , and the inner periphery  34  of the second blade  30 . 
     The second opening  36  is defined spirally among the second seal side portion  43   a  of the second inlet seal panel  43 , the inner periphery  34  of the second blade  30 , and the inner periphery  24  of the first blade  20 . 
     The first opening  26  and the second opening  36  are juxtaposed in a circumferential direction to have a phase difference of 180° to each other about the rotation center axis O of the drum  10 , each of which has a shape spirally cutting off a semicylindrical surface having the rotation center axis O at the center. 
     As the first inlet seal panel  42  and the second inlet seal panel  43  do not form the tunnel-shaped space between the first blade  20  and the second blade  30 , it is difficult for the ready-mixed concrete (material to be stored) to adhere between the first blade  20  and the second blade  30 . Moreover, as the space between the first blade  20  and the second blade  30  is opened, it is easy to clean between the first blade  20  and the second blade  30  by spraying water thereon, at the time of cleaning the inside of the drum  10 . 
     In the expanded view in  FIG. 5 , the inlet seal panels  142  and  143  according to the conventional apparatus are illustrated by two-dotted chain lines. While the first inlet seal panel  42  and the second inlet seal panel  43  according to this embodiment make the space open between the first blade  20  and the second blade  30  arranged in the front-to-rear direction, the inlet seal panels  142  and  143  according to the conventional apparatus are provided to cover the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction like a tunnel. 
     The first inlet seal panel  42  and the second inlet seal panel  43  according to this embodiment are extended in approximately parallel to the rotation center axis O of the drum  10 , and are formed along a cylindrical surface that is continued from the inlet seal pipe  41 . 
     The extension heights of the first blade  20  and the second blade  30  with respect to the inner wall  12  of the drum  10  are set according to the shapes of the first inlet seal panel  42  and the second inlet seal panel  43  so that the front side seal end portions (front end portions)  42   b  and  43   b  of the first inlet seal panel  42  and the second inlet seal panel  43  are connected without a difference in level to the inner peripheries  24  and  34  of the first blade  20  and the second blade  30 . 
     Thereby, in the vicinity of the opening end  11  of the drum  10 , the heights of the first blade  20  and the second blade  30  are greater on the front side (back side) that is far from the opening end  11 , than on the back side that is closer to the opening end  11 . This makes it possible to prevent the ready-mixed concrete from getting over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30 , in the vicinity of the opening end  11  of the drum  10 . 
     When the drum  10  is rotated normally to stir or mix the ready-mixed concrete, with the ready-mixed concrete being loaded closer to the maximum load, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  gets onto the first inlet seal panel  42 , the second inlet seal panel  43  and the inside of the inlet seal  40 . This makes it possible to prevent the ready-mixed concrete from dropping to the opening end  11  side (outlet space  27 ) of the drum  10 . Namely, in the area where the first inlet seal panel  42  and the second inlet seal panel  43  are not provided, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  drops to the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction, and is transferred back to the front side (back side) of the drum  10  by the rotating first blade  20  and the second blade  30 . This makes it possible to prevent the ready-mixed concrete from flowing toward the opening end  11  side (outlet space  27 ) of the drum  10 . Therefore, it is possible for the drum  10  to secure the load capacity equal to that of the conventional apparatus having the large inlet seal. 
     Next, a second embodiment will be explained with reference to  FIG. 7  to  FIG. 10 . 
       FIG. 7  is a perspective view of the drum viewed from a diagonally rear left direction.  FIG. 8  is a cross-sectional view showing schematic structure of the mixer drum apparatus  9 .  FIG. 9  is an expanded view of the inlet seal  40 .  FIG. 10  is a perspective view of the inlet seal  40 . Structure of the mixer drum apparatus of this embodiment is basically the same as that of the first embodiment, and hence explanations are given only to the parts that are different from those of the first embodiment. Incidentally, the identical reference signs are given to the elements identical to those of the first embodiment. 
     The first inlet seal panel  42  has a first extended portion  42   e  that extends along the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  in front. The second inlet seal panel  43  has a second extended portion  43   e  that extends along the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  in front. 
     The first inlet seal panel  42  has a first seal side portion  42   c  that extends to curve along the reference line L 1  and the inner periphery  34  of the second blade  30 . The second inlet seal panel  43  has a second seal side portion  43   c  that extends to curve along the reference line L 2  and the inner periphery  24  of the first blade  20 . 
     Respective rear ends  42   g  and  43   g  of the first extended portion  42   e  and the second extended portion  43   e  are arranged at the front end  41   a  of the inlet seal pipe  41 . Respective front ends  42   h  and  43   h  of the first extended portion  42   e  and the second extended portion  43   e  are arranged at positions separated from the reference lines L 1  and L 2  of the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  toward the front (back side). 
     Extension widths of the first extended portion  42   e  and the second extended portion  43   e , extending in a rotation circumferential direction of the drum  10  from the reference lines L 1  and L 2 , gradually increase from the rear ends  42   g  and  43   g  toward the front (back side). 
     Extension widths of the first extended portion  42   e  and the second extended portion  43   e , extending in a rotation axis direction of the drum  10  from the inner peripheries  24  and  34  of the first blade  20  and the second blade  30 , gradually increase from the front ends  42   h  and  43   h  toward the rear (opening end  11  side). 
     At the time of stirring or mixing, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  gets onto the first extended portion  42   e  and the second extended portion  43   e  of the first inlet seal panel  42  and the second inlet seal panel  43 . This makes it possible to prevent the ready-mixed concrete from flowing toward the opening end  11  side (outlet space  27 ) of the drum  10 . Therefore, it is possible for the drum  10  to secure the load capacity equal to or greater than that of the conventional apparatus having the large inlet seal. 
     In the expanded view in  FIG. 9 , the first inlet seal panel  42  and the second inlet seal panel  43  of this embodiment are illustrated by solid lines, and the first inlet seal panel  142  and the second inlet seal panel  143  of the conventional apparatus are illustrated by two-dotted chain lines. As the first inlet seal panel  42  and the second inlet seal panel  43  are structured to make the space open between the first blade  20  and the second blade  30  arranged in the front-to-rear direction, it is less likely that the ready-mixed concrete (material to be stored) adheres between the first blade  20  and the second blade  30 , as compared with the first inlet seal panel  142  and second inlet seal panel  143  of the conventional apparatus. Moreover, as the space between the first blade  20  and the second blade  30  is opened, it is easy to clean between the first blade  20  and the second blade  30  by spraying water thereon, at the time of cleaning the inside of the drum  10 . 
     According to this embodiment as described thus far, it is easy to clean the inside of the drum  10 , similarly to the first embodiment, and also it is possible to increase the load capacity to be greater than that of the first embodiment. When the load capacity is the same as that of the first embodiment, it is possible to downsize the drum  10 . 
     Next, a third embodiment will be explained with reference to  FIG. 11 . 
       FIG. 11  is a perspective view of the inlet seal  40 . Structure of the mixer drum apparatus of this embodiment is basically the same as that of the first embodiment, and hence explanations are given only to the parts that are different from those of the first embodiment. Incidentally, the identical reference signs are given to the elements identical to those of the first embodiment. 
     The inlet seal  40  does not have the inlet seal pipe  41  of the first embodiment, and is formed by the first inlet seal panel  42  and the second inlet seal panel  43  only, each having the curved triangular plate shape. 
     The first inlet seal panel  42  is formed in the curved triangular plate shape that extends to connect the first blade connecting portion  24   a  and the inner periphery  34  of the second blade  30 . 
     The first inlet seal panel  42  has the first seal side portion  42   a  that extends from the first blade connecting portion  24   a  in approximately parallel to the rotation center axis O of the drum  10 , the front side seal end portion  42   b  that is connected to the inner periphery  34  of the second blade  30 , and a backside seal end portion  42   c  that connects the first blade connecting portion  24   a  and the second blade connecting portion  34   a . The first blade connecting portion  24   a  becomes a sharply-angled tip end (vertex) of the second inlet seal panel  43 . 
     The second inlet seal panel  43  is formed in the curved triangular plate shape that extends to connect the second blade connecting portion  34   a  and the inner periphery  24  of the first blade  20 . 
     The second inlet seal panel  43  has the second seal side portion  43   a  that extends from the second blade connecting portion  34   a  in approximately parallel to the rotation center axis O of the drum  10 , the front side seal end portion  43   b  that is connected to the inner periphery  24  of the first blade  20 , and a backside seal end portion  43   c  that connects the second blade connecting portion  34   a  and the blade connecting portion  24   a  of the first blade  20 . The second blade connecting portion  34   a  becomes a sharply-angled tip end (vertex) of the first inlet seal panel  42 . Incidentally, the first inlet seal panel  42  and the second inlet seal panel  43  may be structured to include the first extended portion  42   e  and the second extended portion  43   e  that are extended along the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  in front (refer to  FIG. 8 ). 
     Thereby, the first inlet seal panel  42  and the second inlet seal panel  43 , each having the curved triangular plate shape, do not cover the space between the first blade  20  and the second blade  30  that are arranged in the front-to-rear direction like a tunnel. The first seal side portion  42   a  defines the first opening  26  that makes the space open between the first blade  20  and the second blade  30 , and the second seal side portion  43   a  defines the second opening  36  that makes the space open between the first blade  20  and the second blade  30 . 
     At the time of stirring or mixing the mixer drum apparatus  9 , the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  gets onto the first inlet seal panel  42  and the second inlet seal panel  43 , in the vicinity of the opening end  11  of the drum  10 . This makes it possible to prevent the ready-mixed concrete from dropping to the opening end  11  side (outlet space  27 ) of the drum  10 . Namely, in the area where the first inlet seal panel  42  and the second inlet seal panel  43  are not provided, the ready-mixed concrete getting over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30  drops to the space between the first blade  20  and the second blade  30  arranged in the front-to-rear direction, and is transferred back to the front side (back side) of the drum  10  by the rotating first blade  20  and the second blade  30 . This makes it possible to prevent the ready-mixed concrete from flowing toward the opening end  11  side (outlet space  27 ) of the drum  10 . 
     In the area where the first inlet seal panel  42  and the second inlet seal panel  43  are not provided, the space between the first blade  20  and the second blade  30  that are arranged in the front-to-rear direction is opened. As the first inlet seal panel  42  and the second inlet seal panel  43  do not form the tunnel-shaped space between the first blade  20  and the second blade  30 , it is difficult for the ready-mixed concrete to adhere between the first blade  20  and the second blade  30 . Moreover, as the space between the first blade  20  and the second blade  30  is opened, it is easy to clean between the first blade  20  and the second blade  30  by spraying water thereon, at the time of cleaning the inside of the drum  10 . 
     The third embodiment does not have the inlet seal pipe as described above, and therefore, a hopper on a facility side can be inserted in the drum  10  when charging the ready-mixed concrete. Thus, it is possible to accept the specification that does not have the hopper at the inlet of the drum  10 . 
     Outlines, operations and effects of the respective embodiments will be explained. 
     (A) The mixer drum apparatus  9  to stir the material to be stored includes the freely-rotatable drum  10  that has the opening end  11  opened at one end and receives the material to be stored therein, the plurality of blades  20  and  30  that are spirally-shaped and provided inside the drum  10  to have the phase difference, and the inlet seal  40  that is provided at the opening end  11  of the drum  10  and is connected partially to the blades  20  and  30 . The inlet seal  40  located between the blades  20  and  30  forms the openings  26  and  36  causing the material to be stored to pass through (refer to  FIG. 1  to  FIG. 9 ). 
     When charging the ready-mixed concrete according to the above-described structure, the ready-mixed concrete (material to be stored) that is charged into the drum  10  is guided by the inlet seal  40  to the front side (back side) of the drum  10  over the blade tip end portions  21  and  31 . 
     When the drum  10  is rotated normally to stir or mix the ready-mixed concrete, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the blades  20  and  30  gets onto the inlet seal  40 , in the vicinity of the opening end  11  of the drum  10 . This makes it possible to prevent the ready-mixed concrete from being discharged from the opening end  11  of the drum  10 . 
     Meanwhile, when the drum  10  is rotated reversely to discharge the ready-mixed concrete, the ready-mixed concrete is transferred from the front to the rear of the drum  10  by the rotating blades  20  and  30  and discharged from the opening end  11  of the drum  10 . 
     The openings  26  and  36  that are formed by the inlet seal  40  make the space open between the blades  20  and  30  that are arranged in the rotation center axis O direction of the drum  10 , and therefore, the space between the blades  20  and  30  arranged in the front-to-rear direction is not covered by the inlet seal  40  like a tunnel. Thereby, it is difficult for the ready-mixed concrete (material to be stored) to adhere between the blades  20  and  30  that are arranged in the front-to-rear direction of the drum  10 , and it is easy to clean between the blades  20  and  30  that are arranged in the front-to-rear direction of the drum  10 , at the time of cleaning the inside of the drum  10 . As a result of this, it is possible to prevent deterioration of stirring and mixing performance and discharging performance of the mixer drum apparatus  9  due to the material adhered to the blades  20  and  30 . 
     (B) The inlet seal  40  has the seal side portions  42   a  and  43   a  that define the openings  26  and  36  to make the space open between the blades  20  and  30  arranged in the rotation center axis O direction of the drum  10  (in the front-to-rear direction of the drum  10 ), and the seal side portions  42   a  and  43   a  extend in the approximately linear manner along the reference lines L 1  and L 2  extending in approximately parallel to the rotation center axis O of the drum  10  (refer to  FIG. 5 ). 
     According to the above-described structure, the seal side portions  42   a  and  43   a  make the space open between the blades  20  and  30  arranged in the front-to-rear direction of the drum  10 . Thereby, it is difficult for the ready-mixed concrete (material to be stored) to adhere between the blades  20  and  30  that are arranged in the front-to-rear direction of the drum  10 , and it is easy to clean between the blades  20  and  30  that are arranged in the front-to-rear direction of the drum  10 , at the time of cleaning the inside of the drum  10 . 
     As the seal side portions  42   a  and  43   a  extend in approximately parallel to the rotation center axis O of the drum  10 , the heights of the blades  20  and  30  are formed greater on the front side (back side) that is far from the opening end  11 , than on the back side that is closer to the opening end  11 . This makes it possible to prevent the ready-mixed concrete from getting over the inner peripheries  24  and  34  of the first blade  20  and the second blade  30 , in the vicinity of the opening end  11  of the drum  10 . Therefore, it is possible for the drum  10  to secure the load capacity equal to that of the conventional apparatus having the large inlet seal. 
     (C) The inlet seal  40  has the blade connecting portions  24   a  and  34   a  that are connected to the blades  20  and  30 , in the vicinity of the opening end  11  of the drum  10 , and is formed to have the curved triangular plate shapes extending from the blade connecting portions  24   a  and  34   a  to the blades  30  and  20  located on the back side of the drum  10  (refer to  FIG. 11 ). 
     According to the above-described structure, the inlet seal  40  in the curved triangular plate shapes does not have the inlet seal pipe. Therefore, the hopper on the facility side can be inserted in the drum  10  when charging the ready-mixed concrete. Thus, it is possible to accept the specification that does not have the hopper at the inlet of the drum  10 . 
     Moreover, as the inlet seal  40  does not have the annular inlet seal pipe  41 , simplification of the structure is made possible. 
     (D) The inlet seal panels  42  and  43  have the extended portions  42   e  and  43   e  that are formed along both of the seal side portions  42   a  and  43   a  (reference lines L 1  and L 2 ) and the blades  20  and  30  (refer to  FIG. 7  to  FIG. 10 ). 
     At the time of stirring or mixing according to the above-described structure, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the blades  20  and  30  gets onto the extended portions  42   e  and  43   e  of the inlet seal panels  42  and  43 . This makes it possible to prevent the ready-mixed concrete from flowing toward the opening end  11  side (outlet space  27 ) of the drum  10 . Thus, it is possible to realize both of the cleaning performance and loading performance of the drum  10 . 
     (E) The inlet seal  40  has the annular inlet seal pipe  41  that is connected to the blades  20  and  30 , and the inlet seal panels  42  and  43  that extend from the inlet seal pipe  41  to the blades  20  and  30  arranged on the back side of the drum  10 , in the vicinity of the opening end  11  of the drum  10  (refer to  FIG. 1  to  FIG. 6 ). 
     According to the above-described structure, the charged ready-mixed concrete is guided by the inlet seal pipe  41  to the inside of the drum  10 . Further, at the time of stirring or mixing, the ready-mixed concrete that gets over the inner peripheries  24  and  34  of the blades  20  and  30  gets onto the inlet seal panels  42  and  43 , in the vicinity of the opening end  11  of the drum  10 . This makes it possible to prevent the ready-mixed concrete from being discharged from the opening end  11  of the drum  10 . 
     Moreover, the inlet seal panels  42  and  43  make the space open between the blades  20  and  30 , and therefore, the space between the blades  20  and  30  arranged in the front-to-rear direction is not covered by the inlet seal  40  like a tunnel. Thereby, it is difficult for the ready-mixed concrete (material to be stored) to adhere between the blades  20  and  30  that are arranged in the front-to-rear direction of the drum  10 , and it is easy to clean between the blades  20  and  30  at the time of cleaning the inside of the drum  10 . 
     The embodiments of the present invention described above are merely illustration of some application examples of the present invention and not of the nature to limit the technical scope of the present invention to the specific constructions of the above embodiments. 
     For example, the mixer drum apparatus  9  according to the above-described embodiments has the pair of first blade  20  and second blade  30 , but it may be structured to have only one blade. In this case, the inlet seal has one inlet seal panel that has the seal side portion defining the opening to make the space open in one blade arranged in the rotation center axis O direction. 
     Alternatively, the mixer drum apparatus  9  may include three or more blades. In this case, the inlet seal has three or more inlet seal panels that have the seal side portions forming three or more openings for making the space open in the three or more blades arranged in the rotation center axis O direction. 
     Moreover, the material to be stored received in the mixer drum apparatus  9  is not limited to the ready-mixed concrete, and other material to be stored may be received. 
     The present application claims a priority based on Japanese Patent Application No. 2011-257640 filed with the Japan Patent Office on Nov. 25, 2011, all the contents of which are hereby incorporated by reference.