Patent Publication Number: US-2022220970-A1

Title: Variable impeller for pump

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2021-0004117, filed Jan. 12, 2021, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates generally to a variable impeller for a pump and, more particularly, to a variable impeller capable of adjusting the length of an impeller vane in response to the pumping head of a pump. 
     Description of the Related Art 
     When the size of a pump is determined for purchasing the pump, the actual head and the loss head are calculated. The difference between the maximum discharge level and the suction level is applied to calculation of the actual head, and the loss generated when a pipe is deteriorated is applied to calculation of the loss head, and a purchase specification is given to manufacture the pump so that the highest efficiency is achieved at the total head. 
     When the pump newly installed according to the purchase specification is operated in the field, a significant gap occurs between the rated head at which the highest efficiency occurs and the operating head occurring in the field, so the pump is operated at a lower head rather than a point at which the highest efficiency commonly occurs. In addition, large variation due to season and time may occur in the district heating method, such as unusually increased usage only in winter. 
     When the proportion of the loss head in the total head is large, the pump may deviate from the proper operating range and cause abnormality accompanied by vibration and noise. In the above case, a valve installed at an outlet is operated to generate resistance, i.e., loss. Therefore, conditions of the pump are changed so that the pump is operated at the pumping head within the proper operating range. 
     When only the diameter of an impeller is changed without changing the rotation speed, the power consumption is proportional to the head ratio in proportion to the square of the changed diameter ratio of the impeller. Accordingly, it is important to adjust the diameter of the impeller in order to change the head of the discharged fluid to suit the actual head that is changed during operation in the field and to use only the energy necessary to operate the pump. 
     Therefore, in a conventional impeller having a vane having a predetermined length, the pump cannot be operated within a high efficiency section thereof in response to the flow rate of fluid, and the power loss of the pump is increased and the power consumption thereof is increased, thereby wasting energy. 
     Conventionally, in order to solve the energy waste described above, a metal impeller with a different diameter and a different length of the vane is separately prepared, and when the pumping head is changed, the prepared spare metal impeller is replaced with the original installed impeller. The impeller replacement is performed by separating a shaft of the pump and the impeller assembly from the pump and then carefully replacing the precisely assembled impeller and elements related to the impeller under the supervision of a highly skilled technician. In this case, there are problems that the replacement time and cost are increased and a complicated process is accompanied when the pumping head is changed. 
     DOCUMENTS OF RELATED ART 
     (Patent Document 1) KR No. 10-1796581 B1 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and the present invention is intended to propose a variable impeller for a pump, wherein the length of a vane is adjusted in response to the pumping head that is changed by a flow rate of fluid, the pump is operated within a high efficiency section, an expensive impeller rotation speed control device is not required, and energy is reduced by reducing power consumption of the pump. 
     Another objective of the present invention is intended to propose a variable impeller for a pump, wherein, when the present invention is applied to the pump, replacement of an extension wing is quickly completed while only a part of a pump housing is opened to expose only the impeller without separating the entire assembly of the impeller. Whereby, the present disclosure is intended to simplify impeller replacement performed when the pumping head is changed. 
     In order to achieve the above objectives, according to one aspect of the present invention, there is provided a variable impeller for a pump. The variable impeller includes a hub to which a shaft may be mounted; a plurality of vanes radially arranged around the hub outward from the hub; and extension wings tightly locked to the plurality of vanes and extending length of each of the vanes. 
     Each of the extension wings may include: a wing portion being in close contact with an end of the vane and extending the length of the vane; and a support portion including a first support part and a second support part that support the wing portion in upward and downward directions of the wing portion. 
     The variable impeller may include: a first shroud and a second shroud formed by radially extending from a circumference of the hub and supporting the plurality of vanes in upward and downward directions of the shaft. 
     The first support part may include a protrusion protruding toward the first shroud from a surface opposing to a surface supporting the wing portion, and the first shroud may include mounting grooves each formed by depressing a surface of the first shroud for the first support part to be mounted into the mounting groove and coupling holes each formed by further depressing the mounting groove to be coupled to the protrusion of the first support part. 
     The first support part and the second support part may have the same section that may be perpendicular to a direction of the shaft and be aligned parallel to the shaft direction. 
     The second shroud may include mounting holes each having a shape corresponding to a section of the second support part perpendicular to the shaft direction, and the second support part may be positioned in each of the mounting holes. 
     A lower surface of the first support part and a lower surface of the first shroud may be provided on the same level, and an upper surface of the second support part and an upper surface of the second shroud may be provided on the same level. 
     The wing portion may include a contact surface and an extension surface, the contact surface formed in the same shape as an end section of the vane to be in contact with the end section and the extension surface formed by extending from the contact surface in a direction in which the vane may extend outward from the hub. 
     According to the embodiment, the length of the vane is adjusted in response to the pumping head that is changed by a flow rate of fluid, so that the pump can be operated within the high efficiency section, the expensive impeller rotation speed control device is not required, and energy can be reduced by reducing the power consumption of the pump. 
     In addition, according to the present invention, during changing operation of the pumping head, replacement of the extension wing can be quickly completed while only a part of the pump housing is opened to expose only the impeller, whereby, it is possible to simplify the impeller replacement performed when the pumping head is changed. Accordingly, the use of the present invention has effects of reducing impeller replacement time and cost due to simplification of the impeller replacement and of reducing the possibility of operating errors of the pump after the impeller replacement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objectives, features, and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a sectional view showing a pump to which an impeller according to an embodiment of the present invention is mounted; 
         FIGS. 2A to 2C  are perspective views showing an extension wing according to the embodiment of the present invention; 
         FIG. 3  is an enlarged side view showing a main part of the impeller shown in  FIG. 1 ; 
         FIG. 4  is a view showing the impeller shown in  FIG. 1  without a first shroud but with a plurality of extension wings; 
         FIG. 5  is a view showing the impeller shown in  FIG. 4  without the plurality of extension wings; and 
         FIG. 6  is a view showing the impeller shown in  FIG. 1  without a second shroud and the plurality of extension wings. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The above and other objectives, features, and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings. As for reference numerals associated with parts in the drawings, the same reference numerals will refer to the same or like parts through the drawings. It will be understood that, although the terms “first”, “second”, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Hereinafter, in the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments. 
     Hereinbelow, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same reference numerals will refer to the same or like elements. 
     Prior to the description, in the embodiment, it is shown that a variable impeller is mounted to a double suction type centrifugal pump, but the variable impeller according to the present invention may be applied to a single suction type centrifugal pump, an axial flow type pump, a diagonal flow type pump, etc. 
     In addition, in various embodiments, elements having the same configuration will be representatively described in the embodiment by using the same reference numerals, and in other embodiments, configurations different from the embodiment will be described. 
     In  FIGS. 1 to 6 , a variable impeller  1  for a pump according to the embodiment of the present invention is shown. 
     The variable impeller  1  is rotatably provided in a housing (not shown) for the pump having an inlet into which a fluid is suctioned and an outlet through which the fluid is discharged. 
     The variable impeller  1  is configured to supply kinetic energy to the fluid suctioned through the inlet due to the rotation of a shaft R and to discharge the fluid through the outlet. 
     According to the embodiment of the present invention, the variable impeller  1  for the pump includes: a hub  100  to which the shaft R is mounted; a plurality of vanes  200  radially arranged around the hub  100  toward the outside of the hub  100 ; and extension wings  300  tightly locked to the plurality of vanes  200  and extending a length of each of the vanes. 
     As shown in  FIGS. 1 to 6 , the variable impeller  1  according to the embodiment of the present invention the pump includes the hub  100 , the plurality of vanes  200 , and the extension wings  300 . 
     The hub  100  has a hollow circular sectional shape and positioned at a center portion of the impeller  1 . The hub  100  is coupled to the shaft R passing therethrough and is rotated together with the shaft R. 
     The plurality of vanes  200  is radially arranged around the hub  100  outward from the hub  100  at intervals. Each of the vanes  200  has a predetermined length, and has a curved shape starting from an outer circumference the hub  100  with respect to a radial direction of the hub  100 , for example, an arc shape with a predetermined radius of curvature. Each of the vanes  200  may have a length capable of discharging the fluid to the lowest head for the pump, for example, an effective rotation radius. In the embodiment, the vane  200  is illustrated with having an arc shape curved with respect to the radial direction of the hub  100 , but the present invention is not limited thereto and the vane  200  may be formed in a linear shape. 
     The extension wings  300  are arranged to be in close contact with the plurality of vanes  200 , respectively. The extension wings  300  are arranged in the impeller  1  to be coupled to ends of the vanes  200  and variably adjust lengths of the vanes  200 . Each of the extension wings  300  is in close contact with each of the vanes  200  in a longitudinal direction of the vane  200 . As shown in  FIGS. 2A to 2C , the variable extension wings  300  having different length may be coupled to the impeller  1 , and thus, in response to change in the amount of fluid discharged from the pump due to seasonal and economic fluctuations, the extension wings  300  may be replaced with different types of extension wings  300 . The extension wings  300  will be described below in detail. 
     As shown in  FIG. 2A to 2C , the extension wings  300  according to the embodiment of the present invention is shown. 
     In the variable impeller  1  for the pump according to the embodiment of the present invention, the extension wing  300  may include: a wing portion  310  being in close contact with an end of the vane  200  and extending a length of the vane  200 ; and a support portion  320  consisting of a first support part  321  and a second support part  322  that support the wing portion  310  in upward and downward directions. 
     In the variable impeller  1  for the pump according to the embodiment of the present invention, the wing portion  310  may include a contact surface  311  formed in the same shape as an end surface  210  of the vane  200  to be in contact with the end surface  210  and an extension surface  312  formed by being extended from the contact surface  311  in a direction in which the vane  200  is extended outward from the hub  100 . 
     According to the embodiment of the present invention, the extension wing  300  includes the wing portion  310  and the support portion  320 . 
     The wing portion  310  serves to extend a length of the vane  200  by being in close contact with the end of the vane  200 . The wing portion  310  has an arc shape having the same radius of curvature as the vane  200 . An end of the wing portion  310  positioned in the opposite direction to the vane  200  may have a pointed shape to minimize pressure loss when the fluid passes through the impeller  1 . The wing portion  310  will be described in detail with reference to  FIGS. 2A to 2C . An outer surface of the wing portion  310  may consist of the contact surface  311  and the extension surface  312 . 
     The contact surface  311  is formed in the same shape as the end surface  210  of the vane  200  to be in contact with the end surface  210 . As shown in  FIG. 3 , side surfaces of the extension wing  300  and the vane  200  are connected to each other without unevenness. Therefore, the vane  200  and the wing portion  310  may be in close contact to be connected smoothly, so that the fluid flow may be streamlined along the vane  200  and the wing portion  310  and turbulence that interferes with the fluid flow and causes energy loss is minimized. 
     The extension surface  312  may be formed in an arc shape to have the same radius of curvature as the vane  200 . The extension surface  312  may be formed in a smooth curved surface, and may have a protruding center portion as shown in  FIGS. 2A to 2C , so that the wing portion  310  may be formed to have the thickest thickness at the extension surface  312  and may be formed to have a thinner thickness as the wing portion  310  goes outward from the extension surface  312 . The above-described shape of the extension surface  312  of the wing portion  310  is designed for the fluid flow minimizing energy loss, and the shape of the extension surface  312  is not limited thereto. 
     The extension wings  300  having the wing portion  310  with different lengths are shown in  FIGS. 2A to 2C . That is, when a length of the vane  200  is required to be adjusted at the time where the amount of fluid is changed due to seasonal and economic fluctuations, the extension wings  300  having the wing portion  310  with the appropriate length may be selected and coupled to or separated from the impeller  1 . 
     The support portion  320  includes the first support part  321  and the second support part  322 . As shown in  FIGS. 2A to 2C , the first support part  321  and the second support part  322  support and fix the wing portion  310  in upward and downward directions. The upward and downward directions is a direction in which the shaft R is extended in  FIG. 1 , thereby the support portion  320  may be formed to support the wing portion  310  in a direction of the shaft R. The wing portion  310  and the support portion  320  may be integrally formed with each other, but are not limited thereto. 
     Arrangement between the vane  200 , the extension wings  300 , and a shroud  400  according to the embodiment of the present invention is shown in  FIGS. 4 to 6 . 
     According to the embodiment of the present invention, the variable impeller  1  for the pump may include a first shroud  410  and a second shroud  420  that are extended from a circumference of the hub  100  in a radial direction of the hub  100 , and support the plurality of vanes  200  in upward and downward directions of the shaft R. 
     According to the embodiment of the present invention, in the variable impeller  1  for the pump, the first support part  321  may have a protrusion  321   a  protruding toward the first shroud  410  from the opposite surface to a wing portion  310  supporting surface. The first shroud  410  may include mounting grooves  411  formed by depressing a surface of the first shroud  410  for the first support part  321  to be mounted thereto and coupling holes  412  further depressed from the mounting grooves  411  to be coupled to the protrusion  321   a.    
     The plurality of vanes  200  is supported by a pair of shrouds  400 . The pair of shrouds  400  is provided by being radially extended from the hub  100  with the vanes  200  positioned between the pair of shrouds  400 , and supports opposite ends of each of the vanes  200 . The shrouds  400  support the vanes  200  in upward and downward directions of the shaft R. The pair of shrouds  400  includes the first shroud  410  and the second shroud  420 . The pair of shrouds  400  is formed in a size larger than an effective rotation radius of each vane  200  in consideration of length extension of the extension wing  300  mounted to the vane  200 . Each of the shrouds  400  is preferably formed to have a radius same as or larger than a rotation radius of the extension wing  300  mounted to the vane  200 . 
     The pair of shrouds  400  is provided in the embodiment. However, the present invention may not be limited thereto, one shroud  400  may be provided in response to a type for the pump. 
     In  FIG. 6 , the first shroud  410  is shown as a view taken from a lower side thereof. The first shroud  410  may include the mounting grooves  411  and the coupling holes  412 . Each of the mounting grooves  411  is a groove into which the first support part  321  is mounted, and is formed by depressing a lower surface of the first shroud  410 . Accordingly, the mounting groove  411  and the first support part  321  may be formed to have sectional shapes correspond to each other. Each of the coupling holes  412  is configured to be coupled to the protrusion  321   a  of the first support part  321  so that the first support part  321  is locked to the first shroud  410 . The protrusion  321   a  protrudes from the surface opposing to the surface supporting the wing portion  310  in the first support part  321  toward the first shroud  410 . A coupling method between the protrusion  321   a  and the coupling hole  412  may be performed by the male and female coupling such as screwing, fitting, etc., but the present invention is not limited thereto. 
       FIGS. 4 to 6  are views showing arrangement between the vanes  200 , the extension wings  300 , and the shrouds  400  according to the embodiment of the present invention. 
     In the variable impeller  1  for the pump according to the embodiment of the present invention, the first support part  321  and the second support part  322  may match each other in sections perpendicular to the direction of the shaft R and may be aligned in the direction of the shaft R. 
     In the variable impeller  1  for the pump according to the embodiment of the present invention, the second shroud  420  may include mounting holes  421  each having a shape corresponding to a section of the second support part  322  perpendicular to the direction of the shaft R, and the second support part  322  may be positioned in each of the mounting holes  421 . 
     In the variable impeller  1  for the pump according to the embodiment of the present invention, a lower surface of the first support part  321  and the lower surface of the first shroud  410  may be provided on the same level, and an upper surface of the second support part  322  and an upper surface of the second shroud  420  may be provided on the same level. 
     According to the embodiment of the present invention, the first support part  321  and the second support part  322  of the support portion  320  may be aligned parallel to the direction of the shaft R, and may be formed to have the same shapes in sections perpendicular to the direction of the shaft R. As described above, when the first support part  321  and the second support part  322  are arranged parallel to each other, the extension wings  300  may be easily replaced in the impeller  1 . When the extension wings  300  are mounted to the impeller  1 , as the first support part  321  and the second support part  322  pass through in sequence the mounting holes  421  to be described later, the extension wings  300  may be mounted to the impeller  1 . Furthermore, when the extension wings  300  are separated from the impeller  1 , the second support part  322  passes through the mounting holes  421  and then the first support part  321  passes through the mounting holes  421 , whereby the impeller  1  and the extension wings  300  may be separated from each other. Through the replacement method, the extension wings  300  may be removed from and mounted to the impeller  1  without separation of the hub  100 , the vanes  200 , the shrouds  400 , etc., so that replacement time and cost of the extension wings  300  may be drastically reduced. In other words, during replacement of the impeller  1 , replacement of the extension wings  300  may be quickly completed while only a casing for the pump is opened and only the impeller  1  is exposed. Accordingly, replacement of the impeller  1  performed when the pumping head is changed may be simplified. Therefore, the use of the present invention causes an effect of lowering the possibility of an operation error for the pump after replacement of the impeller  1  due to simplification of the impeller replacement. Furthermore, the performance of the impeller  1  may be changed by simply replacing the extension wings  300  without replacement of the impeller  1 . 
     The structure of the second shroud  420  according to the embodiment of the present invention is shown in  FIGS. 4 and 5 . The second shroud  420  may include the mounting holes  421 . Each of the mounting holes  421  may be formed in a hole passing through a surface of the second shroud  420 . The mounting hole  421  may be formed on the surface of the second shroud  420  with a shape corresponding to a section of the second support part  322  in the perpendicular direction to the shaft direction. Accordingly, as the shapes of the mounting hole  421  and the second support part  322  match to each other, the second support part  322  may be positioned in the mounting hole  421 . When the shapes of the mounting hole  421  and the second support part  322  match to each other, voids on the surface of the second shroud  420  are minimized during positioning of the second support part  322  in the mounting hole  421 , so that mechanical vibration, turbulence of fluid, and performance degradation of the impeller  1  may be minimized. 
     According to the embodiment of the present invention, the lower surface of the first support part  321  and the lower surface of the first shroud  410  may be provided on the same level. When the first support part  321  is positioned in the mounting groove  411 , the surface of the first support part  321  and the surface of the first shroud  410  may be provided on the same level. Therefore, during fluid flow, turbulence generated when fluid touches the surface of the first shroud  410  may be minimized. According to another embodiment of the present invention, the first support part  321  and the mounting groove  411  may be formed to have the same thickness. As described above, a structure that satisfies the condition in which the lower surface of the first support part  321  and the lower surface of the first shroud  410  are positioned on the same level may be another embodiment of the present invention. 
     According to the embodiment of the present invention, the upper surface of the second support part  322  and the upper surface of the second shroud  420  may be provided on the same level. When the second support part  322  is positioned in the mounting hole  421 , the surface of the second support part  322  and the surface of the second shroud  420  may be positioned on the same level. Therefore, during fluid flow, turbulence generated when fluid touches the surface of the second shroud  420  may be minimized. In another embodiment of the present invention, the second support part  322  and the mounting hole  421  may be formed to have the same thickness. As described above, a structure that satisfies the condition in which the upper surface of the second support part  322  and the upper surface of the second shroud  420  may be positioned on the same level may be another embodiment of the present invention. 
     By using the variable impeller  1  having the above-describe configuration for the pump according to the embodiment of the present invention, the process of variably adjusting the length of the vane  200  will be described below. 
     First, in order to discharge fluid at the rated head which is the highest head by using the impeller  1  according to the embodiment of the present invention, as shown in  FIG. 3 , the extension wings  300  are tightly coupled to the ends of the vanes  200  so that each of the vanes  200  of the impeller  1  has a rotation radius corresponding to the rated head. As shown in  FIG. 2A , as the extension wings  300  coupled to the impeller  1 , the extension wing  300  having the longest wing portion  310  may be adopted. Whereby, the length of the vane  200 , for example, the effective rotation radius of the vane  200  may be maximized 
     After the impeller  1  with the extension wings  300  respectively coupled to the vanes  200  is tested under a dynamic balance test to adjust the rotation balance, the impeller  1  is assembled to the pump housing. 
     When the impeller  1  assembled to the pump housing rotates the shaft R by a driving means (not shown), the impeller  1  is rotated. Then, a pressure difference is generated in a fluid inlet area of the vane  200  so that the fluid inflowing through the inlet for the pump housing flows into the vane  200 . When the fluid flowing into the vane  200  flows along the vane  200  and the extension wing  300  as centrifugal force is applied by the rotational force of the vane  200 , and is discharged at the rated head through the outlet for the pump housing. 
     Next, in order to discharge fluid at the lowest head by using the impeller  1  according to the embodiment of the present invention, as shown in  FIG. 5 , the extension wings  300  are not coupled to the ends of the vane  200  so that each of the vanes  200  of the impeller  1  has a rotation radius corresponding to the desired lowest head. Whereby, the length of the vane  200 , for example, the effective rotation radius of the vane  200  is minimized. 
     After the impeller  1  without the extension wings  300  is tested under the dynamic balance test to adjust the rotation balance, the impeller  1  is assembled to the pump housing. 
     When the shaft R is rotated, the impeller  1  is rotated. Therefore, the fluid flows through the inlet for the pump housing and flows along the vanes  200  as centrifugal force is applied due to rotational force of the vanes  200 , so that the fluid may be discharged through the outlet for the pump housing at the desired lowest head. 
     Meanwhile, in order to discharge fluid at a predetermined head within a section between the rated head and the lowest head by using the impeller  1  according to the embodiment of the present invention, as shown in  FIGS. 2B and 2C , the extension wing  300  with the wing portion  310  having a middle length is tightly coupled to the end of the vane  200  so that the vane  200  of the impeller  1  has a rotation radius corresponding to the desired predetermined head. Accordingly, depending on the type of the extension wing  300  coupled to the impeller  1  while being in close contact with the vane  200 , the length of the vane  200  is variably adjusted, for example, the effective rotation radius of the vane  200  is variably adjusted. 
     As described above, the impeller  1  in which the plurality of extension wings  300  of a desired type are tightly mounted to the vanes  200  is tested under the dynamic balance test to adjust the rotation balance, and is assembled to the pump housing. 
     Then, when the shaft R is rotated, the impeller  1  is rotated. Whereby, the fluid flows through the inlet of the pump housing and flows along the vanes  200  and the extension wings  300  as centrifugal force is applied due to rotation force of the vanes  200 , and is discharged at the desired predetermined head through the outlet of the pump housing. 
     As described above, according to the present invention, the length of the vane is adjusted in response to the pumping head that is changed by a flow rate of fluid, so that the pump may be operated within a high efficiency section, an expensive impeller rotation speed control device may not be required, and energy may be reduced by reducing the power consumption of the pump. 
     Hereinabove, although the preferred embodiments of the present invention have been described for illustrative purposes, the present invention is not limited thereto, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 
     All modifications and variations of the present invention belong to the scope of the present invention, and the specific protective scope of the present invention will be clearly understood by the accompanying claims.