Patent Publication Number: US-6655914-B2

Title: Casing cover and pump device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a casing cover for use in separating a motor assembly and a pump assembly from each other in a pump device such as a circulating pump for handling fresh water, and a pump device having such a casing cover. 
     2. Description of the Related Art 
     Pump devices such as a circulating pump for handling fresh water are required to prevent the liquid that is being handled under an increased pressure in a pump casing from leaking out of a high-pressure opening in the pump casing into a motor assembly. To meet such a requirement, it has widely been customary to separate a motor assembly and a pump assembly from each other with a casing cover with a mechanical seal mounted therein for sealing a main shaft and also to seal the pump casing in a water-tight fashion with an O-ring, for example. 
     FIG. 1 of the accompanying drawings shows, in enlarged fragmentary cross section, a fixed region of a casing cover in a conventional general pump device, the casing cover being formed by pressing a stainless steel plate, for example. The casing cover, generally denoted by  10 , has a flat panel portion  12 , a cylindrical wall portion  14 , and a flange portion  16  which are integrally formed by pressing a flat plate. The cylindrical wall portion  14  has an inner circumferential surface serving as a motor-side faucet-joint surface (motor-side positioning portion)  14   a  held against a motor bracket  20  and an outer circumferential surface serving as a pump-side faucet-joint surface (pump-side positioning portion)  14   b  held against a pump casing  22 . The motor-side faucet-joint surface  14   a,  i.e. the motor-side register fit surface  14   a,  is fitted over the motor bracket  20 , and the pump-side faucet-joint surface  14   b,  i.e. the pump-side register fit surface  14   b,  is fitted in the pump casing  22 , providing a faucet-joint structure, i.e. a socket-and-spigot joint (positioning) structure. 
     Since the inner and outer circumferential surfaces of the cylindrical wall portion  14  are fitted over and in the motor bracket  20  and the pump casing  22 , when the flat plate is pressed to form the cylindrical wall portion  14 , one of the inner and outer circumferential surfaces of the cylindrical wall portion  14 , e.g., the inner circumferential surface, is used as a dimensional reference to achieve desired dimensional accuracy. 
     However, in the conventional casing cover  10 , when the flat plate is pressed to form the cylindrical wall portion  14 , one of the inner and outer circumferential surfaces of the cylindrical wall portion  14 , e.g., the inner circumferential surface, is used as a dimensional reference, since the flat plate generally suffers thickness variations, it is difficult to achieve desired dimensional accuracy for the other of the inner and outer circumferential surfaces of the cylindrical wall  14 , e.g., the outer circumferential surface. Furthermore, when the pump device is serviced for maintenance, e.g., when the mechanical seal is replaced, because the casing cover  10  tends to stick to the motor bracket  20  and the pump casing  22  due to rust or the like, it is difficult to remove the casing cover  10  while both the inner and outer circumferential surfaces of the cylindrical wall portion  14  are being of normal dimensions. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a casing cover which is capable of fitting with members of both a motor assembly and a pump assembly highly accurately in providing a faucet-joint (positioning) structure, and of disassembling and removing a member thereof held in interfitting faucet-joint (positioning) engagement with the members of the motor assembly and the pump assembly while keeping normal dimensions, and a pump device having such a casing cover. 
     According to the present invention, there is provided a casing cover for use in separating a motor assembly and a pump assembly from each other in a pump device, comprising: a cylindrical wall portion having a step, a motor-side positioning portion positioned on one side of the step for being fitted to a member of the motor assembly, and a pump-side positioning portion positioned on the other side of the step for being fitted to a member of the pump assembly. 
     Since the motor-side positioning portion and the pump-side positioning portion are individually positioned one on each side of the step of the cylindrical wall portion, the casing cover can be formed by pressing a flat plate using both the motor-side positioning portion and the pump-side positioning portion as dimensional references, both the motor-side positioning portion and the pump-side positioning portion can be formed to shape with high dimensional accuracy. The casing cover with such high dimensional accuracy can be assembled easily and quickly in the pump device, and can be disassembled and removed while the motor-side positioning portion and the pump-side positioning portion are being dimensionally maintained. 
     The motor-side positioning portion may comprise a motor-side faucet-joint surface, and the pump-side positioning portion may comprise a pump-side faucet-joint surface, thereby providing a faucet-joint structure. 
     The motor-side faucet-joint surface may be disposed on one of an inner and outer circumferential surface of the cylindrical wall portion, and the pump-side faucet-joint surface may be disposed on the other of the inner and outer circumferential surface of the cylindrical wall portion. 
     According to the present invention, there is also provided a pump device comprising: a motor assembly; a pump assembly; and a casing cover separating the motor assembly and the pump assembly from each other; the casing cover comprising a cylindrical wall portion having a step, a motor-side positioning portion positioned on one side of said step for being fitted to a member of the motor assembly, and a pump-side positioning portion positioned on the other side of said step for being fitted to a member of the pump assembly. 
     The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate a preferred embodiment of the present invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an enlarged fragmentary cross-sectional view of a faucet-joint (positioning) structure in a conventional pump device; 
     FIG. 2 is an axial cross-sectional view of a pump device according to an embodiment of the present invention; and 
     FIG. 3 is an enlarged fragmentary cross-sectional view of a faucet-joint (positioning) structure in the pump device shown in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in FIGS. 2 and 3, a pump device according to an embodiment of the present invention has a motor assembly M and a pump assembly P. The motor assembly M has a high-pressure opening in which there is disposed a casing cover  10  that separates the motor assembly M and the pump assembly P from each other. The casing cover  10  has its circumferential edge gripped and secured in position between a motor bracket  20  that is mounted on an end of the motor assembly M closer to the pump assembly P and a pump casing  22  of the pump assembly P. 
     The motor assembly M has a main shaft  30  extending toward the pump assembly P. The main shaft  30  is sealed by a mechanical seal  32  mounted on an inner circumferential surface of the casing cover  10  and extends into the pump casing  22 . An impeller  34  is fixed to the end of the main shaft  30  which is positioned in the pump casing  22 . 
     The pump casing  22  has a suction port  24  defined in one end thereof and a discharge port  26  defined in the other end thereof. A liner ring  36  is fixed, as by pressing, to an end face of the pump casing  22  which surrounds an outer circumferential surface of a suction end of the impeller  34 . With the liner ring  36  being thus positioned, there is defined a restriction between the outer circumferential surface of the suction end of the impeller  34  and an inner circumferential surface of the liner ring  36 . The restriction has a given gap and separates a higher-pressure region and a lower-pressure region within the pump casing  22 . 
     When the motor assembly M is energized, the impeller  34  disposed in the pump casing  22  rotates in unison with the main shaft  30 , drawing a liquid which is being handled from the suction port  24  into the pump casing  22 . The liquid drawn into the pump casing  22  is then pressurized by the impeller  34 , and then discharged out of the pump casing  22  through the discharge port  26 . 
     The casing cover  10  comprises a press-formed product that is formed by pressing a stainless steel plate, for example, and has a flat panel portion  12 , a cylindrical wall portion  14 , a flange portion  16 , and a mechanical seal holder portion  18  which holds the mechanical seal  32  therein. The cylindrical wall portion  14  has an annular step  14   c  positioned somewhere in the axial longitudinal direction of the cylindrical wall portion  14 . The cylindrical wall portion  14  includes a larger-diameter region on one side of the annular step  14   c,  i.e., closer to the motor assembly M, and a smaller-diameter region on the other side of the annular step  14   c,  i.e., closer to the pump assembly P. The cylindrical wall portion  14  also has a motor-side faucet-joint surface (motor-side positioning portion)  14   a,  i.e. the motor-side register fit surface  14   a,  on its inner circumferential surface which is fitted over the motor bracket  20  and a pump-side faucet-joint surface (pump-side positioning portion)  14   b,  i.e. the pump-side register fit surface  14   b,  on its outer circumferential surface which is fitted in the pump casing  22 , thus providing a faucet-joint structure, i.e. a socket-and-spigot joint (positioning) structure. The motor-side faucet-joint surface  14   a  and the pump-side faucet-joint surface  14   b  are disposed respectively in the larger-diameter region and the smaller-diameter region, i.e., respectively on the opposite sides of the annular step  14   c.    
     The casing cover  10  is disposed securely in position between the motor bracket  20  and the pump casing  22 , with the motor-side faucet-joint surface  14   a  being held in interfitting faucet-joint engagement with the motor bracket  20  and the pump-side faucet-joint surface  14   b  being held in interfitting faucet-joint engagement with the pump casing  22 . Therefore, accurate positioning of the motor bracket  20  and the pump casing  22  is obtained through the motor-side faucet-joint surface  14   a  and the pump-side faucet-joint surface  14   b  of the casing cover  10 . 
     Since the motor-side faucet-joint surface (motor-side positioning portion)  14   a  and the pump-side faucet-joint surface (pump-side positioning portion)  14   b  are individually positioned one on each side of the annular step  14   c  of the cylindrical wall portion  14 , the casing cover  10  can be formed by pressing the flat plate using both the motor-side faucet-joint surface  14   a  and the pump-side faucet-joint surface  14   b  as dimensional references. Specifically, the smaller-diameter region of the cylindrical wall portion  14  on one side of the annular step  14   c  is formed using the pump-side faucet-joint surface  14   b  or the outer circumferential surface as a dimensional reference, and the larger-diameter region of the cylindrical wall portion  14  on the other side of the annular step  14   c  is formed using the motor-side faucet-joint surface  14   a  or the inner circumferential surface as a dimensional reference. Accordingly, both the motor-side faucet-joint surface  14   a  and the pump-side faucet-joint surface  14   b  can be pressed to shape with high dimensional accuracy. The casing cover  10  with such high dimensional accuracy can be assembled easily and quickly in the motor bracket  20  and the pump casing  22 . 
     When the pump device is serviced for maintenance, e.g., when the mechanical seal  32  is replaced, even if the casing cover  10  sticks to the motor bracket  20  and the pump casing  22  due to rust or the like, the casing cover  10  can be removed while the pump-side faucet-joint surface  14   b  or the outer circumferential surface of the cylindrical wall portion  14  on one side of the annular step  14   c  is being dimensionally maintained, and the motor-side faucet-joint surface  14   a  or the inner circumferential surface of the cylindrical wall portion  14  on the other side of the annular step  14   c  is being dimensionally maintained. Therefore, the casing cover  10  can be reassembled easily and quickly in the motor bracket  20  and the pump casing  22 . 
     According to the present invention, as described above, the casing cover  10  is capable of fitting with the motor bracket  20  and the pump casing  22  highly accurately in providing a faucet-joint (positioning) structure, and of disassembling and removing the cylindrical wall portion  14  held in interfitting faucet-joint engagement with the motor bracket  20  and the pump casing  22  while keeping normal dimensions and also reassembling the cylindrical wall portion  14  easily and quickly. 
     Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.