Patent Publication Number: US-2007098577-A1

Title: Pump system

Description:
TECHNICAL FIELD  
      The present invention relates to a pump system, and more particularly to a large-sized pump system for delivering water from a river, a reservoir, or the like to another place.  
     BACKGROUND ART  
      When a water level of a river increases due to heavy rain such as storm, the river may be flooded in some cases. In order to prevent such flood of the river, a large-sized pump system (pump plant) has been used to deliver water from the river to another place. A pump incorporated in such a pump system is an axial-flow-type or mixed-flow-type pump having a low pump head and being capable of delivering a large amount of water. This type of pump comprises an impeller disposed in a pump casing. The impeller is rotated by a drive source disposed outside the pump casing through a rotational shaft. Generally, a delivery valve is provided at an outlet side of the pump so as to prevent a fluid from flowing back into the pump when the operation of the pump is stopped.  
      When constructing the aforementioned pump system, the pump is fixed to a mount surface of an installation site by anchor bolts. An inlet-side flange (an inlet mouth) and an outlet-side flange (an outlet mouth) of the pump are connected respectively to an inlet passage and an outlet passage, which have been installed in advance in the installation site, by using bolts and nuts. At this time, centering operation is carried out so as to align the inlet-side flange with the inlet passage, and the outlet-side flange with the outlet passage. The pump and the drive source are assembled in the installation site. When assembling these components, alignment operation is carried out so as to align the rotational shaft and a drive shaft of the drive source with each other.  
      In this manner, the construction of the pump system requires many operations such as the installing of the pump, the centering, and the assembling of the pump and the drive source, which are very laborious and time-consuming. Especially, a high technical ability and experiences are required for a working person to perform the positioning of the components such as the pump and the drive source and the alignment of the rotational shaft and the drive shaft. Further, when performing the maintenance of the pump system, the components should be dismantled and then assembled, resulting in large labor and cost. Furthermore, since the delivery valve is required to be provided at the outlet side of the pump, a constructing cost of the pump system becomes large and the delivery valve should be maintained regularly.  
     DISCLOSURE OF INVENTION  
      The present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a pump system which can greatly reduce the labor, the cost, and the time for the installation and the maintenance.  
      In order to achieve the above object, according to one aspect of the present invention, there is provided a pump system comprising: a pump having an impeller and a drive source which are disposed in a pump casing; at least one pair of support pedestals which are symmetrically disposed on an installation surface for said pump; and a connecting mechanism for connecting the pump to at least one of an inlet passage and an outlet passage, the connecting mechanism being stretchable and contractible.  
      In a preferred aspect of the present invention, the connecting mechanism comprises: a pair of flange members disposed so as to face each other; a stretchable and contractible member for connecting the flange members to each other in a liquid-tight manner; and a relative moving mechanism for moving the flange members relative to each other so as to change a distance between the flange members.  
      According to the present invention, by simply placing the pump onto the pump placement surfaces of the support pedestals, the pump is positioned automatically and accurately. Therefore, the aforementioned centering operation and the installation operation using the anchor bolts can be eliminated. Further, by using the stretchable and contractible connecting mechanism, the pump can be easily connected to the inlet passage and/or the outlet passage without using bolts and nuts. Furthermore, since both the impeller and the drive source are disposed in the pump casing in advance, it is not required to perform the alignment of the rotational shaft of the impeller and the drive shaft of the drive source in the installation site.  
      In a preferred aspect of the present invention, the drive source is a brushless synchronous motor.  
      According to the present invention, the pump can be lightweight, and hence the installation of the pump can be easily carried out.  
      In a preferred aspect of the present invention, a liquid passage including the outlet passage has a siphon shape.  
      According to the present invention, it is possible to prevent the fluid from flowing back into the pump without using the delivery valve. Therefore, the manufacturing and constructing cost of the pump system as a whole can be reduced and the maintenance operation of the delivery valve can be eliminated.  
      According to the present invention, the number of processes required in installing the pump system can be reduced compared to a conventional pump system. Therefore, it is possible to greatly reduce the labor, the cost, and the time spent for the installation of the pump system. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1A  is a cross-sectional view showing a pump system according to a first embodiment of the present invention;  
       FIG. 1B  is a plan view of the pump system shown in  FIG. 1A ;  
       FIG. 2  is a plan view showing a plurality of the pump systems shown in  FIG. 1B ;  
       FIG. 3A  is an enlarged cross-sectional view of a pump shown in  FIG. 1A ;  
       FIG. 3B  is across-sectional view taken along line III-III illustrated in  FIG. 3A ;  
       FIG. 4A  is a front view showing a connecting mechanism incorporated in the pump system according to the embodiment of the present invention;  
       FIG. 4B  is a view showing the connecting mechanism as viewed from a direction indicated by an arrow IVb illustrated in  FIG. 4A ;  
       FIG. 4C  is a cross-sectional view taken along line IVc-IVc illustrated in  FIG. 4B ;  
       FIG. 5A  is an enlarged view showing a part Va illustrated in  FIG. 4A ; and  
       FIG. 5B  is a cross-sectional view taken along line Vb-Vb illustrated in  FIG. 5A . 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      A pump system according to an embodiment of the present invention will be described be low with reference to the drawings.  
       FIG. 1A  is a cross-sectional view showing a pump system according to a first embodiment of the present invention, and  FIG. 1B  is a plan view of the pump system shown in  FIG. 1A .  FIG. 2  is a plan view showing a plurality of the pump systems shown in  FIG. 1B . The arrows A illustrated in  FIG. 1A  indicate a flowing direction of a liquid.  
      As shown in  FIGS. 1A and 1B , a pump system  1  comprises a base  2  having an inlet passage  3  and an outlet passage  4  provided therein, and a pump  5  disposed between the inlet passage  3  and the outlet passage  4 . An installation surface  2   a , which is inclined with respect to a horizontal plane, is formed in the base  2 , and two pairs of support pedestals (support members)  6  are fixedly provided on the installation surface  2   a . The pump  5  is placed on these support pedestals  6 . An inlet mouth  5   a  of the pump  5  is connected to a downstream-side open mouth  3   b  of the inlet passage  3 , and an outlet mouth  5   b  of the pump is connected to an upstream-side open mouth  4   a  of the outlet passage  4  through a connecting mechanism  10 .  
      A liquid passage including the outlet passage  4  has a siphon shape (i.e., an inverted U-shape) In this embodiment, the pump  5  and the outlet passage  4  form a siphon passage. A siphon-breaking valve  7  is provided at a highest position of the outlet passage  4 . When the operation of the pump  5  is stopped, the siphon-breaking valve  7  is activated in order to prevent a liquid from flowing back into the pump  5 .  
      A stop log (i.e., a gate)  11  is provided so as to cover an upstream-side open mouth  3   a  of the inlet passage  3 , and a horizontal bar screen (i.e., a separator)  12  is provided upstream of the stop log  11 . The horizontal bar screen  12  has a plurality of bars (not shown) disposed in parallel, and is provided for allowing only small rocks and rubbishes to pass therethrough. As shown in  FIG. 2 , in an installation site of the pump system, a plurality of the pump systems  1  are installed in parallel.  
       FIG. 3A  is an enlarged cross-sectional view of a pump shown in  FIG. 1A , and  FIG. 3B  is a cross-sectional view taken along line III-III illustrated in  FIG. 3A . As shown in  FIGS. 3A and 3B , the pump  5  comprises a cylindrical pump casing  15 , an axial-flow-type or mixed-flow-type impeller  16  housed in the pump casing  15 , and a drive source  17  for rotating the impeller  16 . The impeller  16  is coupled to the drive source  17  through a rotational shaft  18 , and the drive source  17  is fixed to an inner surface of the pump casing  15  through guide vanes  19 . The pump  5  is installed in such a state that the position of the outlet mouth  5   b  is higher than that of the inlet mouth  5   a  and the rotational shaft  18  is inclined at a predetermined angle with respect to a horizontal plane. The pump  5  is a so-called axial-flow-type or mixed-flow-type tubular pump in which the impeller  16  and the drive source  17  are disposed in the pump casing  15 . This type of pump has features such that a pump head is relatively low and a flow rate of a liquid (i.e., a discharge rate) is high.  
      In this embodiment, a brushless synchronous motor is used as the drive source  17 . The use of the brushless synchronous motor allows the drive source  17  to be lightweight and small in size.  
      As shown in  FIG. 3B , the support pedestals  6  as a pair have the same shape as each other, and are symmetrically disposed about a center line of the pump  5 , i.e., the rotational shaft  18 . Each of the support pedestals  6  has a slope surface (a pump placement surface)  6   a  formed on an upper end portion thereof. The slope surfaces  6   a  are symmetrically inclined with respect to the installation surface  2   a , so that when the pump  5  is placed onto the slope surfaces  6   a , an outer circumferential surface of the pump casing  15  is held in contact with the slope surfaces  6   a.    
      The pump  5  is not fixed to the support pedestals  6  when being installed on the installation surface  2   a , but is simply placed on the slope surfaces  6   a  of the support pedestals  6 . Once the pump  5  is placed on the slope surfaces  6   a , the center line of the pump  5  and the center line between the support pedestals  6  coincide with each other, and the pump  5  is thus positioned automatically. Further, the pump  5  on the slope surfaces  6   a  is moved downwardly along the installation surface  2   a  by gravity until the inlet mouth  5   a  of the pump  5  is brought into contact with the downstream-side open mouth  3   b  of the inlet passage  3 . A relative position between the downstream-side open mouth  3   b  and the support pedestals  6  is adjusted in advance based on the size of the pump  5 , so that centering between the inlet mouth  5   a  and the downstream-side open mouth  3   b  of the inlet passage  3  is performed automatically only by placing the pump  5  onto the slope surfaces  6   a  of the support pedestals  6 .  
      The inlet mouth  5   a  is pressed against the downstream-side open mouth  3   b  by gravity, whereby the inlet mouth  5   a  is connected to the downstream-side open mouth  3   b . An annular seal member (not shown) such as an O-ring is provided on a contact surface of the downstream-side open mouth  3   b  to be brought into contact with the inlet mouth  5   a  so that the downstream-side open mouth  3   b  and the inlet mouth  5   a  are connected in a liquid-tight manner. Although two pairs of the support pedestals  6  are provided in this embodiment, only one pair of support pedestals extending in a longitudinal direction of the pump  5  may be provided, or more than two pairs of support pedestals may be provided. Further, although the slope surfaces  6   a  of the support pedestals  6  have a flat shape in this embodiment, each of the slope surfaces  6   a  may be a curved surface whose shape corresponds to the outer circumferential surface of the pump casing  15 .  
      The outlet mouth  5   b  of the pump  5  is connected to the upstream-side open mouth  4   a  of the outlet passage  4  through the connecting mechanism  10 . This connecting mechanism  10  is stretchable and contractible in a flowing direction of a liquid passing therethrough. Hereinafter, the connecting mechanism  10  will be described with reference to  FIGS. 4A through 4C .  FIG. 4A  is a front view showing a connecting mechanism incorporated in the pump system according to the embodiment of the present invention,  FIG. 4B  is a view showing the connecting mechanism as viewed from a direction indicated by an arrow IVb illustrated in  FIG. 4A , and  FIG. 4C  is a cross-sectional view taken along line IVc-IVc illustrated in  FIG. 4B .  
      As shown in  FIGS. 4A through 4C , the connecting mechanism  10  comprises a pair of flange members  20  disposed so as to face each other, a stretchable and contractible member  21  for connecting the flange members  20  to each other in a liquid-tight manner, a relative moving mechanism  22  for moving the flange members  20  relative to each other so as to change a distance between the flange members  20 , and a plurality of (four, in this embodiment) slide guides  23  for guiding a movement of the flange members  20 . The relative moving mechanism  22  comprises a plurality of (two, in this embodiment) drive motors (geared motors)  24 , a plurality of (four, in this embodiment) gear mechanisms  25  for converting rotational motion into linear motion, and a plurality of (two, in this embodiment) driveshafts  26  for coupling the drive motors  24  to the gear mechanisms  25 .  
      The flange members  20  and the stretchable and contractible member  21  have a substantially elliptical shape. The stretchable and contractible member  21  may preferably comprise a rubber having a high flexibility and a high waterproofing property. This stretchable and contractible member  21  is fixed to inner surfaces of the flange members  20  which face each other, and has a U-shaped cross section so as to easily stretch and contract. The flange members  20  are thus connected through the stretchable and contractible member  21 .  
      The gear mechanism  25  and the slide guide  23  are disposed adjacent to each other and are arranged along a circumferential direction of the flange members  20  at substantially equal intervals. The two drive motors  24  are disposed in the vicinity of side surfaces of the flange members  20  and positioned symmetrically about a center of the flange members  20 . Each of the drive motors  24  is coupled to the two gear mechanisms  25  through the drive shaft  26  so that power of the drive motor  24  is transmitted to the gear mechanisms  25  through the drive shaft  26 .  
       FIG. 5A  is an enlarged view showing a part Va illustrated in  FIG. 4A , and  FIG. 5B  is a cross-sectional view taken along line Vb-Vb illustrated in  FIG. 5A .  
      As shown in  FIGS. 5A and 5B , the gear mechanism  25  comprises a screw shaft  30  extending perpendicularly to the flange members  20 , a worm wheel  31  fixed to the screw shaft  30 , a worm  32  meshing with the worm wheel  31 , and a female screw member  33  in which the screw shaft  30  is threaded. The worm wheel  31  and the worm  32  are housed in a first gear casing  34 , and the female screw member  33  is housed in a second gear casing  35 . The first gear casing  34  is fixed to one of the two flange members  20 , and the second gear casing  35  is fixed to the other.  
      As shown in  FIG. 5A , bearings  37  for rotatably supporting the screw shaft  30  are provided in the first gear casing  34 , and the worm wheel  31  is disposed between these bearings  37 . As shown in  FIG. 5B , the worm  32  is fixed to a support shaft  38  that is rotatably supported by bearings  39  disposed in the first gear casing  34 . The support shaft  38  is coupled to the drive shaft  26  through a shaft coupling  40 . The drive shaft  26  may be extended so that the worm  32  is fixed to the extended portion of the drive shaft  26 .  
      A male screw  30   a  is formed on a circumferential surface of the screw shaft  30 , and a female screw  33   a  is formed on an inner circumferential surface of the female screw member  33 . A plurality of balls (not shown) are provided between the male screw  30   a  and the female screw  33   a , so that when the screw shaft  30  is rotated, the balls circulate while being brought into rolling contact with the male screw  30   a  and the female screw  33   a . A set of the screw shaft  30  and the female screw member  33  having the above structure is called a ball screw which can reduce a friction loss and can improve a power-transmission efficiency.  
      The slide guide  23  is disposed near the gear mechanism  25 . This slide guide  23  comprises a column-shaped slide member  41  extending perpendicularly to the flange members  20 , a cylindrical guide bush  42  for guiding a movement of the slide member  41 , and a housing  43  for housing the guide bush  42 . The slide member  41  is fixed to one of the two flange members  20 , and the housing  43  is fixed to the other. The slide member  41  is smoothly fitted into the guide bush  42 , and is movable relative to the guide bush  42 . A moving direction of the slide member  41  relative to the guide bush  42  corresponds to a moving direction of the screw shaft  30  relative to the female screw member  33 .  
      With this structure, when the drive motor  24  (see  FIG. 4B ) is energized, the power of the drive motor  24  is transmitted to the worm wheel  31  through the drive shaft  26  and the worm  32 , thus rotating the worm wheel  31  and the screw shaft  30  integrally. As the screw shaft  30  rotates, this screw shaft  30  moves relative to the female screw member  33 , whereby the distance between the flange members  20  is changed. The two drive motors  24  illustrated in  FIG. 4B  are controlled so as to rotate synchronously at the same rotational speed, whereby the flange members  20  are moved while keeping parallel to each other.  
      The connecting mechanism  10  having the above structure is disposed between the outlet mouth  5   b  of the pump  5  and the upstream-side open mouth  4   a  of the outlet passage  4  (see  FIG. 3A ). When installing the connecting mechanism  10 , the drive motors  24  moves the flange members  20  to increase the distance between the flange members  20 , so that the one of the flange members  20  is brought into contact with the outlet mouth  5   b  of the pump  5  and the other is brought into contact with the upstream-side open mouth  4   a  of the outlet passage  4 . The flange members  20  are pressed against the outlet mouth  5   b  of the pump  5  and the upstream-side open mouth  4   a  of the outlet passage  4 , respectively, by the drive motors  24  and the gear mechanisms  25 , whereby the outlet mouth  5   b  and the upstream-side open mouth  4   a  are connected through the connecting mechanism  10  in a liquid-tight manner. It is desirable to provide an annular seal member on at least one of the contact surfaces of the flange members  20  to be brought into contact with the outlet mouth  5   b  and the upstream-side open mouth  4   a . An o-ring is preferably used as the seal member.  
      The flange members  20  and the stretchable and contractible member  21  may have a circular shape or a rectangular shape instead of a substantially elliptical shape as in this embodiment. Specifically, the shape of the flange members  20  and the stretchable and contractible member  21  is determined according to the shape of the outlet mouth  5   b  of the pump  5  and the upstream-side open mouth  4   a  of the outlet passage  4 . Although the aforementioned connecting mechanism  10  comprises the gear mechanisms  25  and the drive motors  24  as the relative moving mechanism  22 , one or more power cylinder mechanisms utilizing a pressure of a fluid such as a gas may be used as the relative moving mechanism.  
      Although the pump  5  of this embodiment is a so-called inclined pump in which the pump  5  is obliquely installed, the present invention is also applicable to a so-called horizontal pump in which the pump is horizontally installed. In the case of the horizontal pump, it is desirable to provide the aforementioned connecting mechanisms at both the outlet side and the inlet side of the pump. With such an arrangement, the inlet mouth and the outlet mouth of the pump can be connected respectively to the downstream-side open mouth of the inlet passage and the upstream-side open mouth of the outlet passage in a liquid tight manner. In this case also, the centering between the inlet mouth of the pump and the downstream-side open mouth of the inlet passage and between the outlet mouth of the pump and the upstream-side open mouth of the outlet passage can be performed automatically by simply placing the pump onto the slope surfaces (i.e., the pump placement surfaces).  
     INDUSTRIAL APPLICABILITY  
      The present invention is applicable to a pump system for delivering water from a river, a reservoir, or the like to another place.