Patent Publication Number: US-9841030-B2

Title: Vertical self-priming pump

Description:
TECHNICAL FIELD 
     The present invention relates to pump, specifically to a vertical self-priming pump. 
     BACKGROUND ART 
     The self-priming pump is capable of starting to work at the situation that the liquid inlet pipe is not filled with liquid medium (but the must be enough liquid medium in the pump body) and automatically exhausting gas in the liquid inlet pipe. When the pump is started for the first time, there must be enough liquid medium added into the pump body of the self-priming pump; after this, the self-priming pump can start again by the liquid medium remaining in the pump body. The self-priming pump can be divided into two types according to working principle, including internal mixing type and external mixing type. The internal mixing type self-priming pump means that the gas-liquid mixing is carried out near the inlet of the impeller, while the external mixing type self-priming pump means that the gas-liquid mixing is carried out at the outer edge of the impeller. Structure of the external mixing type self-priming pump is as shown in  FIG. 1 . Before the initial startup, the pump cavity is filled with water at first; after startup, the impeller  1  rotates at a high speed to eliminate liquid medium in the impeller flow channel  2 , so as to form negative pressure at the liquid inlet opening of the impeller  1  to suck gas in the liquid inlet pipe  4  into the pump cavity and form gas-liquid mixture with the liquid medium in the pump cavity; and the gas-liquid mixture is discharged to the gas-liquid separation chamber on top of the pump cavity through the impeller flow channel  2  on the impeller; because the exit area of the impeller flow channel  2  becomes big suddenly, the flow velocity decreases suddenly, so the gas separates from the liquid and is discharged from the water outlet pipe  5  on the pump body; and the liquid medium sinks and flows back to the outer edge of the impeller  1  through the backflow gap  3  because it is heavy, and it continues to mix with gas sucked in from the impeller flow channel  2 ; all gas in the liquid inlet pipe  4  can be gradually discharged after repeated circulation to make the liquid medium enter into the pump cavity and finish the self-priming process. 
     However, because there is a backflow gap  3  in the self-priming pump structure, the remaining medium keeps circulating under action of the pressure, which causes big loss in volume efficiency. The test shows that the loss is about  8 %, which lowers down the efficiency of the self-priming pump seriously. Besides, the self-priming pump cannot reach the normal flow and pump head, and energy consumption is increased. 
     SUMMARY OF THE INVENTION 
     The present invention aims to solve the technical problem that the self-priming pump is low in efficiency. 
     In order to solve the above problem, the present invention provides a vertical self-priming pump that comprises a pump body, a motor and a medium backflow blocking device. 
     The inner cavity of the pump body is divided into a gas-liquid separation chamber and a liquid storage chamber through a middle partition plate that is provided with an axial inlet opening, and the gas-liquid separation chamber is above the liquid storage chamber; a flow guide body is fixed on the upper surface of the middle partition plate; the flow guide body is provided with an axial through hole and a radial flow guide hole that is in communication with the axial through hole, and the gas-liquid separation chamber is in communication with the liquid storage chamber through the axial inlet opening and the radial flow guide hole on the flow guide body; a motor, which is fixed on the top of the pump body for driving a pump shaft that vertically downward penetrates into the inner cavity of the pump body to rotate, and an impeller that is arranged in the axial through hole of the flow guide body is fixed on the lower end of the pump shaft; a backflow gap channel is formed between the outer circumferential surface of the impeller and the inner wall of the axial through hole of the flow guide body; further comprising a medium backflow blocking device that comprises a static ring and a moving ring which are vertically and oppositely arranged as well as an elastic supporting sleeve; the moving ring is embedded on the upper surface of the impeller, and the outer edge of the elastic supporting sleeve extends downwards to form a supporter that is fixed on the upper surface of the flow guide body; the static ring is embedded on the lower surface of an elastic supporting ring, and the lower end surface of the static ring protrudes the lower surface of the elastic supporting sleeve, and a gap is formed between the lower end surface of the static ring and the upper end of the moving ring. 
     In the above proposal, the self-priming pump further comprises a flow-blocking depressurization plate; upper part of the impeller is in a step-like axle shape with top part smaller than lower part, and the flow-blocking depressurization plate is in a step-like sleeve shape with top part bigger than the lower part and provided with an axle hole; the flow-blocking depressurization plate is vertically sleeved on the impeller with the big-diameter part fixed on the flow guide body; a backflow gap channel is formed by the gap between inner wall of the axle hole of the flow-blocking depressurization plate and outer circumferential surface of the small-diameter part of the impeller and the gap between the lower end surface of the flow-blocking depressurization plate and step surface of the impeller. 
     In the above proposal, the size of the backflow gap channel is 0.3-0.5 mm. 
     In the above proposal, the gap channel between the lower end surface of the flow-blocking depressurization plate and step surface of the impeller is provided with a downwards slant dip angle. 
     In the above proposal, the dip angle is 3-8 degrees. 
     In the above proposal, the inner wall of axle hole of the flow-blocking depressurization plate is provided with a plurality of circular grooves. 
     In the above proposal, the moving ring and the static ring are separately made of hard alloy, silicon carbide, ceramic, graphite or polytetrafluoroethylene. 
     In the present invention, a medium backflow blocking device is provided on the upper surface of the impeller. During normal working, the elastic supporting sleeve of the present invention in the medium backflow blocking device generates a downward deformation under the action of liquid medium pressure, thus the moving ring and the static ring closely contact with each other and block the backflow gap channel, therefore the volume loss generated by the backflow is avoided, and the pump efficiency can be improved by 5%-8%. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is the structure diagram of the existing vertical self-priming pump; 
         FIG. 2  is the structure diagram of the first specific implementation method of the vertical self-priming pump provided in the present invention; 
         FIG. 3  is the structure diagram of the second specific implementation method of the vertical self-priming pump provided in the present invention; 
         FIG. 4  is the installation diagram of the medium backflow blocking device of the vertical self-priming pump provided in the present invention; 
         FIG. 5  is the enlarged drawing of part A in  FIG. 3 ; 
         FIG. 6  is the schematic diagram of medium backflow of the second vertical self-priming pump provided in the present invention in startup status; 
         FIG. 7  is the schematic diagram of medium backflow of the second vertical self-priming pump provided in the present invention in normal working status. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The vertical self-priming pump provided in the present invention improves the working efficiency through the medium backflow blocking device. During the startup and vacuumizing process of the self-priming pump, the medium backflow blocking device does not take effect; when the vacuum izing process is finished and the self-priming pump works normally, because the pressure in the gas-liquid separation chamber is enlarged, the backflow gap channel is blocked through the medium backflow blocking device, so as to reduce the backflow loss of the self-priming pump and improve the working efficiency. The following is detailed description to the present invention combining drawings and embodiments. 
       FIG. 2  is the structure diagram of the first specific implementation method of the vertical self-priming pump provided in the present invention. As shown in  FIG. 2 , the vertical self-priming pump provided in the present invention comprises a pump body  10 , a motor  20  and a medium backflow blocking device  30 . 
     The pump body  10  comprises an inner cavity that is vertically divided into a gas-liquid separation chamber  12  and a liquid storage chamber  13  through a middle partition plate  11 ; a liquid inlet pipe  14  is arranged on the gas-liquid separation chamber  12 , and the liquid outlet pipe  14  is provided with check valve  15 ; the liquid storage chamber  13  is provided with a liquid inlet pipe  16  that is provided with a vacuum breaking valve  17 . 
     The middle partition plate  11  is provided with an axial inlet opening, and a flow guide body  40  is fixed on the upper surface of the middle partition plate  11 ; the flow guide body  40  is provided with an axial through hole and a radial flow guide hole  41  that is in communication with the axial through hole, the medium backflow blocking device  30  is provided on the upper surface of the flow guide body  40 ; the gas-liquid separation chamber  12  is in communication with the liquid storage chamber  13  through the axial inlet opening  18  and the radial flow guide hole  41  on the flow guide body  40 . 
     A motor  20  is fixed on the top of the pump body  10  for driving a pump shaft  21  that vertically downward penetrates into the inner cavity of the pump body  10  to rotate, and an impeller  22  that is arranged in the axial through hole of the flow guide body  40  is fixed on the lower end of the pump shaft  21 ; an impeller channel  23  is provided inside the impeller  22 , and inlet of the impeller channel  23  is in communication with the liquid storage chamber  13  through the axial inlet hole  18 , and the outlet of the impeller channel  23  is in communication with the gas-liquid separation chamber  12  through the radial flow guide hole  41  on the flow guide body  40 ; a backflow gap channel  24  is formed between the outer circumferential surface of the impeller  22  and the inner wall of the axial through hole of the flow guide body  40 ; the size of the backflow gap channel  24  is 0.3-0.5 mm. 
     As shown in  FIG. 4 , the medium backflow blocking device  30  comprises a static ring  32  and a moving ring  31  which are vertically and oppositely arranged as well as an elastic supporting sleeve  33 ; the moving ring  31  is embedded on the upper surface of the impeller  22 , and the upper surface of the moving ring  31  is higher than that of the impeller  22 ; the elastic supporting sleeve  33  comprises a round main body with outer edge extending downwards to form a supporter  34  that is provided with a flange at the lower end, and the flange is fixed on the upper surface of the flow guide body  40  through a pressing block  35 ; the static ring  32  is embedded on the lower surface of main body of the elastic supporting sleeve  33 , and the lower end surface of the static ring  32  protrudes the lower surface of main body of the elastic supporting sleeve  33 . The end surfaces of the moving ring  31  and the static ring  32  that are opposite to each other are processed by mirror grinding and provided with gap, and the material thereof can be hard alloy, silicon carbide, ceramic, graphite or F 4  (polytetrafluoroethylene) for different mediums. 
     It is well known that the impeller of the vertical self-priming pump is easy to be worn. The outer circumferential surface of the impeller is easy to be worn in use; in order to reduce cost of replacing the impeller; the present invention improves the structure of impeller. The specific improvement is as shown in  FIG. 3  that is the structure diagram of the second specific implementation method of the vertical self-priming pump provided in the present invention; and  FIG. 4  is the installation diagram of the medium backflow blocking device. As shown in  FIG. 3  and  FIG. 4 , the difference of this embodiment from the first embodiment is that a flow-blocking depressurization plate  50  is arranged on the impeller  22 , and the respective structure of impeller  22  is also changed accordingly as follows: upper part of the impeller  22  is in a step-like axle shape with top part smaller than lower part, and the flow-blocking depressurization plate  50  is in a step-like sleeve shape with top part bigger than the lower part and provided with an axle hole; the flow-blocking depressurization plate  50  is vertically sleeved on the impeller  22  with the big-diameter part fixed on the flow guide body  40 ; a backflow gap channel  24  is formed by the gap between inner wall of the axle hole of the flow-blocking depressurization plate  50  and outer circumferential surface of the small-diameter part of the impeller  22  and the gap between the lower end surface of the flow-blocking depressurization plate  50  and step surface of the impeller  22 . Besides, the gap channel between the lower end surface of the flow-blocking depressurization plate  50  and step surface of the impeller  22  is provided with a downwards slant dip angle α which is 3-8 degrees. 
     Further, the inner wall of axle hole of the flow-blocking depressurization plate  50  is provided with a plurality of circular grooves  52  (as shown in  FIG. 5 ) to function as diffusion and depressurization. 
     The following is description of the use process of the vertical self-priming pump provided in the present invention combining  FIG. 6  and  FIG. 7 . 
     As shown in  FIG. 6 , during the startup and vacuumizing process of the self-priming pump, the elastic supporting sleeve  33  is under action of its elastic force, and the moving ring  31  is separated from the static ring  32 , thus the liquid medium separated from the gas-liquid separation chamber  12  goes down and enters the cavity G enclosed by the elastic supporting sleeve  33 , the impeller  22 , the flow-blocking depressurization plate  50  and the upper surface of the flow guide body  40  as well as the moving ring  31  and static ring  32  through the gap between the moving ring  31  and static ring  32 , and flows back to outlet of the impeller channel  23  of the impeller  22  through the backflow gap channel  24  between the outer circumferential surface of the impeller  22  and the flow-blocking depressurization plate  50 , so as to carry out liquid-gas mixing with the gas that is sucked into the liquid storage chamber  13  from the liquid inlet pipe  16  and then delivered through the axial inlet hole  18  and the impeller channel  23 ; at last the mixture is discharged to the gas-liquid separation chamber  12  through the radial flow guide hole  41  on the flow guide body  40  to carry out gas-liquid separation; such process is repeatedly circulated to keep discharging the gas in the liquid inlet pipe  16  to finish the vacuum izing startup process. The arrow direction in  FIG. 6  is the flow direction of liquid medium. 
     As shown in  FIG. 7 , when the impeller  22  continuously discharges the liquid medium in the liquid storage chamber  13  into the gas-liquid separation chamber  12 , the pressure of the liquid medium in the gas-liquid separation chamber  12  increases continuously and takes effect on the upper surface of the elastic supporting sleeve  33  and makes it generate downward deformation, because the backflow gap channel  24  is very shallow (0.3-0.5 mm), the liquid medium generates big resistance loss when passing by, and the plurality of circular grooves  52  in the backflow gap channel  24  enlarges the flow space of medium suddenly to further decrease pressure in the backflow gap channel; as a result, the pressure of medium in cavity G is much lower than that in the gas-liquid separation chamber  12 , which helps the elastic supporting sleeve  33  to generate downward deformation and press lower surface of the static ring  32  to be in close fit with upper surface of the moving ring  31 , thus to form sealing and block backflow of the liquid medium. As a result, the volume loss generated by the circulating backflow is avoided, and the pump efficiency is improved by 5% to 8%. The arrow direction in  FIG. 7  is the flow direction of liquid medium. The gap channel between the lower end surface of the flow-blocking depressurization plate  50  and step surface of the impeller  22  is provided with a downwards slant dip angle to generate bigger pressure loss and increase the pressure difference between the cavity G and the gas-liquid separation chamber  12 , and the slant dip angle a, which is 3-8 degrees, is the best angle obtained by the inventor after a large number of experiments. This angle realizes that it would not make impeller generate big vibration due to impact while enlarging the pressure difference. The plurality of circular grooves  52  can also enlarge the pressure difference between the cavity G and the gas-liquid separation chamber  12 . 
     When the vertical self-priming pump stops working, the check valve  15  is closed quickly to block backflow of the high liquid medium in the liquid outlet pipe  14 ; at the same time, the vacuum breaking valve  17  on the liquid inlet pipe  16  is synchronously opened so that gas enters into the liquid inlet pipe  16  to break the vacuum status thereof; therefore, the problem that all liquid medium in the pump flows back and drains because of siphonage is completely avoided. As a result, the liquid storage chamber  13  is always remaining a part of pumped liquid medium, so as to realize the self-priming forever goal of the self-priming pump after drainage for once. 
     The present invention is not limited by the above best implementation way. Any structural change inspired by the present invention and any technical proposal that is same as or similar with the present invention should belong to the protection scope of the present invention.