Exhaust device, water pump and design method

Abstract

The present application relates to an exhaust device, a water pump and a design method, and relates to the technical field of water pumps, including a pump cover, a guide pipe for guiding water flow to a mechanical seal is provided on the pump cover, and the guide pipe includes a water inlet section and a water outlet section, the water inlet section is arranged at the outer edge of the impeller, and the water outlet section is arranged at the mechanical seal. The present application has the advantage of being able to reduce space occupation.

Description

Technical Field

[0001] The present application relates to the technical field of water pumps, and in particular to an exhaust device, a water pump and a design method. Background Art

[0002] When an existing centrifugal pump is running, as the flow rate increases, more air is brought into the pump when the water is sucked in, causing the air to quickly accumulate at the pump cover to form an air pocket. The mechanical seal is often installed in the center of the pump cover, so air will accumulate at the mechanical seal and cause dry wear and damage to the mechanical seal.

[0003] For example, a dry vertical mounted sewage pump with automatic exhaust function disclosed in the Chinese utility model patent with announcement number CN218542616U adopts a solution of exhausting air by connecting an exhaust pipe; a single-stage centrifugal pump mechanical seal cooling and flushing device disclosed in the Chinese invention patent with announcement number CN101509504B adopts a flushing form for cooling the mechanical seal; the above solutions all adopt an external pipeline to exhaust gas or flush the mechanical seal, which increases the space occupied. Summary of the invention

[0004] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide an exhaust device, a water pump and a design method, which have the advantage of being able to reduce space occupancy.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0006] An exhaust device comprises a pump cover, on which a guide pipe for guiding water flow to a mechanical seal is provided.

[0007] In a preferred example, the present application can be further configured as follows: the flow guide pipe includes a water inlet section and a water outlet section, the water inlet section is arranged at the outer edge of the impeller, and the water outlet section is arranged at the mechanical seal.

[0008] In a preferred example, the present application can be further configured as follows: the opening of the water inlet section faces the direction of water flow.

[0009] In a preferred example, the present application can be further configured as follows: the opening of the water outlet section faces the friction surface of the mechanical seal or is tangent to the outer cylindrical surface of the mechanical seal.

[0010] In a preferred example, the present application can be further configured as follows: the opening of the water outlet section faces the axis or follows the rotation direction of the water flow.

[0011] In a preferred example, the present application can be further configured as follows: the guide pipe also includes a guide section, the water inlet section and the guide section are connected with a bend pipe, and the guide section and the water outlet section are connected with a bend pipe. The axes of the guide section and the water inlet section are extended to intersect at point A, and the axes of the guide section and the water outlet section are extended to intersect at point B. The center of the pump shaft is O, and the direction of rotation along the water flow is set to be positive. When the OA line is used as the baseline, point B is located on the side of OA rotating in the positive direction with O as the center or on the OA line.

[0012] In a preferred example, the present application can be further configured as follows: a baffle is also provided on the pump cover, and the baffle is located below the mechanical seal.

[0013] In a preferred example, the present application can be further configured as follows: the opening diameter of the water inlet section is not smaller than the opening diameter of the water outlet section.

[0014] The present application also discloses a water pump which adopts the above-mentioned exhaust device.

[0015] The present application also discloses a design method for calculating the relationship between the diameter and length of the flow guide pipe, determining the average peripheral pressure P1 of the water inlet port, unit Pa, the average peripheral pressure P2 of the water outlet port, unit Pa, and the flow rate V of the water inlet port. A , unit m / s, outlet port flow velocity V B , unit m / s, assuming the total length of the diversion pipe is L, unit m, calculate the inlet flow rate V1 of the diversion pipe, unit m / s, and the outlet flow rate V2 of the diversion pipe, unit m / s, at this time V1=V A ;

[0016] Calculate the average flow velocity in the flow tube according to the Bernoulli equation:

[0017]

[0018] ——density, kg / m 3 ;

[0019] g——acceleration due to gravity, N / kg;

[0020] V2 is obtained, and the average flow velocity in the guide tube is v=1 / 2 (V1+V2);

[0021] Calculate the maximum head loss h w :

[0022] By maximum pressure drop ; ;

[0023] Calculate the local head loss and get the local head loss:

[0024]

[0025] ——local loss coefficient (dimensionless);

[0026] Head loss along the way ;

[0027] Calculate the head loss along the way according to the Darcy Weisbach formula:

[0028]

[0029] ——longitudinal resistance coefficient (dimensionless);

[0030] d——pipeline diameter, m;

[0031] Substitute to get the maximum pipe diameter:

[0032] Diameter of the flow pipe .

[0033] This application has the following advantages:

[0034] By setting a guide pipe so that it corresponds to the outer edge of the impeller, part of the water flow enters the guide pipe with an initial velocity under the action of pressure, and then rushes to the mechanical seal from the water outlet section of the guide pipe, squeezing out the gas gathered at the mechanical seal, thereby preventing air accumulation at the mechanical seal from causing dry grinding of the mechanical seal; at the same time, the guide pipe is used to form a self-circulating exhaust method in the pump cover, which can be achieved by welding the guide pipe on the original pump cover without the need for external piping, which will not increase the complexity of parts and space occupancy, and reduce the local head loss caused by the bend in the guide pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the cross-sectional structure of the water pump of this application.

[0036] Figure 2 This is a schematic diagram of the straight pipe structure of the flow guide pipe in the present application.

[0037] Figure 3 This is a schematic diagram of a folded tube structure in which the guide tube of the present application is a folded tube structure.

[0038] Figure 4 This is a schematic diagram of the structure in which the guide pipe of the present application is a curved pipe.

[0039] Figure 5 This is a schematic diagram of ∠AOB being zero in this application.

[0040] Figure 6 This is a schematic diagram showing that ∠AOB is not zero in this application.

[0041] Figure 7 This is the pressure cloud diagram of end A of this application.

[0042] Figure 8 This is the pressure cloud diagram of end B of this application.

[0043] Fig. 9 This is the pressure cloud diagram at end A when the baffle is present in this application.

[0044] Fig.10 This is the pressure cloud diagram at end B when the baffle is present in this application.

[0045] Figure numerals: 1. Pump cover; 2. Guide pipe; 21. Water inlet section; 22. Guide section; 23. Water outlet section; 3. Impeller; 4. Mechanical seal; 5. Baffle. DETAILED DESCRIPTION

[0046] The following is combined with Figure 1 -Attached Fig.10 This application is described in further detail.

[0047] The present application discloses an exhaust device, including a pump cover 1, on which a guide pipe 2 for guiding water flow to a mechanical seal 4 is provided, the guide pipe 2 including a water inlet section 21 and a water outlet section 23, the water inlet section 21 being arranged at the outer edge of the final impeller 3, the water outlet section 23 being arranged at the mechanical seal 4, the opening of the water inlet section 21 facing the direction of the water flow, the opening of the water outlet section 23 facing the friction surface of the mechanical seal 4 or tangent to the outer cylindrical surface of the mechanical seal 4, and the opening of the water outlet section 23 facing the axis or following the rotation direction of the water flow. The opening diameter of the water inlet section 21 is not less than the opening diameter of the water outlet section 23, which can increase the flow rate entering the guide pipe 2 and increase the water outlet flow rate V2, thereby making the water flow rushing to the mechanical seal 4 faster and making it easier to discharge the air gathered at the mechanical seal 4.

[0048] Reference Figure 2 and Figure 3 The guide tube 2 can be a straight tube or a folded tube, that is, there can be a pressure difference at both ends of the guide tube 2. When there is a pressure difference, water will flow through the guide tube 2 to hit the machine seal 4 to discharge the air at the machine seal 4.

[0049] See also Figure 4-6 , the guide pipe 2 can also be a curved pipe. When it is a curved pipe, the guide pipe 2 also includes a guide section 22. The water inlet section 21 is connected to the guide section 22 by a curved pipe, and the guide section 22 is connected to the water outlet section 23 by a curved pipe. The axes of the guide section 22 and the water inlet section 21 are extended to intersect at point A, and the axes of the guide section 22 and the water outlet section 23 are extended to intersect at point B. The center of the pump shaft is O, and the direction of rotation along the water flow is set to be positive, that is, ∠AOB≥0°. When the OA line is taken as the baseline, point B is located on the side of OA rotating in the positive direction with O as the center or on the OA line. This setting reduces the local head loss caused by the curved pipe in the guide pipe 2. The pump cover 1 is also provided with a baffle 5, which is vertically arranged and located below the mechanical seal 4.

[0050] See also Figure 7 and Figure 8 , the end face of the mechanical seal 4 facing the last-stage impeller 3 is set as end A, and the inner end face of the pump cover 1 is set as end B, and the pressure cloud diagram is obtained, the average pressure at end A is 100887Pa, and the average pressure at end B is 100313Pa; it can be concluded that there is a positive pressure difference corresponding to the discharge end of the last-stage impeller 3 and the mechanical seal 4, that is, there is a pressure difference between the opening of the water inlet section 21 and the opening of the water outlet section 23 of the guide pipe 2. Therefore, under the action of the initial velocity and pressure difference of the water entering the guide pipe 2, the water entering the guide pipe 2 is guided by the guide pipe 2 and then rushes to the friction surface of the mechanical seal 4, so that the air accumulated at the mechanical seal 4 is discharged from the pump body along with the water flow.

[0051] The baffle plate 5 can further reduce the accumulation of air at the mechanical seal 4 and block impurities. The pressure cloud diagram with the baffle plate 5 is shown in FIG. Fig. 9 and Fig.10 , the A end and the B end also have a positive pressure difference, and are also applicable to the above-mentioned solution of using the guide tube 2 to reduce the air accumulation at the mechanical seal 4.

[0052] The present application also discloses a water pump which adopts the above-mentioned exhaust device.

[0053] A design method, characterized in that it is used to calculate the relationship between the diameter and length of the guide pipe 2, determine the average peripheral pressure P1 of the port of the water inlet section 21, the average peripheral pressure P2 of the port of the water outlet section 23 (unit Pa) and the flow rate V of the port of the water inlet section 21 A , flow rate V at port 23 of the outlet section B (unit m / s), assuming the total length of the diversion pipe 2 is L (unit m), calculate the water inlet flow rate V1 of the diversion pipe 2, and the water outlet flow rate V2 of the diversion pipe 2. At this time, V1=V A ;

[0054] Calculate the average flow velocity in the flow guide tube 2 according to the Bernoulli equation:

[0055]

[0056] ——density, kg / m 3 ;

[0057] g——acceleration due to gravity, N / kg;

[0058] V2 is obtained, and the average flow velocity in the flow guide tube 2 is v=1 / 2 (V1+V2);

[0059] Calculate the maximum head loss h w :

[0060] By maximum pressure drop ; ;

[0061] Calculate the local head loss and get the local head loss:

[0062]

[0063] ——local loss coefficient (dimensionless);

[0064] Head loss along the way ;

[0065] Calculate the head loss along the way according to the Darcy Weisbach formula:

[0066]

[0067] ——longitudinal resistance coefficient (dimensionless);

[0068] d——pipeline diameter, m;

[0069] Substitute to get the maximum pipe diameter:

[0070] Diameter of flow guide pipe 2 .

[0071] The implementation principle of this embodiment is: the guide pipe 2 is made to correspond to the outer edge of the impeller 3, and part of the water flows into the guide pipe 2 through the pressure and initial velocity there, and then rushes to the mechanical seal 4 from the water outlet section 23 of the guide pipe 2, and squeezes out the gas gathered at the mechanical seal 4, thereby preventing the mechanical seal 4 from being dry-grinded due to air accumulation; at the same time, the guide pipe 2 is used to form a self-circulating exhaust method in the pump cover 1, which can be achieved by welding the guide pipe 2 on the original pump cover 1, without the need for external pipelines, and will not increase the complexity of parts and space occupancy, and reduce the local head loss caused by the bend in the guide pipe.

[0072] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for designing an exhaust device, characterized in that: It is used to calculate the relationship between the diameter and length of the flow guide pipe (2), determine the average peripheral pressure P1 of the port of the water inlet section (21), in Pa, the average peripheral pressure P2 of the port of the water outlet section (23), in Pa, and the flow rate V at the port of the water inlet section (21) A , unit m / s, outlet port flow velocity V B , unit m / s, assuming the total length of the diversion pipe (2) is L, unit m, calculate the water inlet flow rate V1 of the diversion pipe (2), unit m / s, and the water outlet flow rate V2 of the diversion pipe (2), unit m / s, at this time V1=V A ; Calculate the average flow velocity in the flow guide tube (2) using the Bernoulli equation: ——density, kg / m 3 ; g——acceleration due to gravity, N / kg; V2 is obtained, and the average flow velocity in the guide tube is v=1 / 2 (V1+V2); Calculate the maximum head loss h w : By maximum pressure drop ; ; Calculate the local head loss and get the local head loss: ——local loss coefficient; Head loss along the way ; Calculate the head loss along the way according to the Darcy Weisbach formula: —— resistance coefficient along the way; d——pipeline diameter, m; Substitute to get the maximum pipe diameter: Diameter of the flow guide tube (2) .

2. An exhaust device, designed by the exhaust device design method according to claim 1, characterized in that: The pump cover (1) comprises a guide pipe (2) for guiding water flow toward a mechanical seal (4).

3. An exhaust device according to claim 2, characterized in that: The flow guide pipe (2) comprises a water inlet section (21) and a water outlet section (23); the water inlet section (21) is arranged at the outer edge of the impeller (3), and the water outlet section (23) is arranged at the mechanical seal (4).

4. An exhaust device according to claim 3, characterized in that: The opening of the water inlet section (21) faces the direction of water flow.

5. An exhaust device according to claim 3, characterized in that: The opening of the water outlet section (23) faces the friction surface of the mechanical seal (4) or is tangent to the outer cylindrical surface of the mechanical seal (4).

6. An exhaust device according to claim 3, characterized in that: The opening of the water outlet section (23) faces the axis or follows the rotation direction of the water flow.

7. An exhaust device according to claim 3, characterized in that: The flow guide pipe (2) further comprises a guide section (22), the water inlet section (21) and the guide section (22) are connected by a curved pipe, and the guide section (22) and the water outlet section (23) are connected by a curved pipe. The axes of the guide section (22) and the water inlet section (21) are extended to intersect at point A, and the axes of the guide section (22) and the water outlet section (23) are extended to intersect at point B. The center of the circle where the pump shaft is located is O, and the direction of rotation along the water flow is set as positive. When the OA connecting line is taken as the baseline, point B is located on the side of OA rotating in the positive direction with O as the center or on the OA connecting line.

8. An exhaust device according to claim 2, characterized in that: The pump cover (1) is also provided with a baffle plate (5), and the baffle plate (5) is located below the mechanical seal (4).

9. An exhaust device according to claim 3, characterized in that: The opening diameter of the water inlet section (21) is not less than the opening diameter of the water outlet section (23).

10. A water pump, characterized in that: An exhaust device as described in any one of claims 2 to 8 is used.

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