Small-flow shield pump

Abstract

The utility model discloses a small-flow shield pump, which belongs to the field of shield pumps and comprises a motor outer shell, a motor stator and rotor assembly is assembled in the motor outer shell, an auxiliary impeller is mounted at the tail of the rotor assembly, a pump body assembly is assembled at the front end of the motor outer shell, and a full-open impeller is arranged in the pump body assembly. The main circulating hydraulic power of the shield pump is designed to be a tangent pump, the impeller is designed to be in a full-open type, and the impeller is designed to be a straight blade, so that the efficiency of the shield pump is higher than that of a centrifugal pump when the impeller diameter is the same and the specific rotating speed is low and the flow is small. The internal circulation is high-pressure circulation, and the auxiliary impeller at the tail part of the rotor assembly pressurizes the circulating medium again, so that the internal circulating medium is kept at high pressure, and medium viscosity reduction caused by mass temperature rise is prevented. A magnetic coupler is utilized, a fan impeller assembly is driven by a rotor assembly, normal-temperature air is pressurized and forced to circulate, a motor outer shell is cooled, and long-term stable operation of the motor is ensured.

Description

Technical Field

[0001] The utility model relates to the field of canned pumps, in particular to a small-flow canned pump. Background Technique

[0002] A canned pump is a special leak-free pump, which is composed of a canned motor and a pump integrated together, and is widely used in industries such as chemical industry, petrochemical industry, and medicine, especially suitable for the transportation of flammable, explosive, toxic, corrosive, and precious liquids. The working principle of the canned pump is to seal the pump and the driving motor in a pressure vessel filled with the pumped medium, and provide a rotating magnetic field and drive the rotor through a wire group. This structure cancels the rotating shaft sealing device of the traditional centrifugal pump and realizes complete leak-free.

[0003] In the pharmaceutical industry or chemical laboratories, small-flow canned pumps are usually used to transport small-flow strong corrosive, toxic, flammable, and precious media. However, due to the small flow rate of the canned pump, the hydraulic efficiency is low; the internal circulation volume is small. The low hydraulic efficiency will cause the temperature of the medium to rise after the impeller does work. The small internal circulation of the pump will cause the temperature of the canned motor coil to rise, and then premature aging and damage; the rise in the temperature of the internal circulation medium will cause the viscosity of the medium to decrease, and then cause insufficient lubrication of the sliding bearing and damage. Both will cause the small-flow canned pump to fail to work properly.

[0004] Improving the hydraulic efficiency of small-flow canned pumps and reducing the motor temperature are crucial for the normal operation of small-flow canned pumps. Existing small-flow canned pumps improve the hydraulic efficiency by changing from a single large impeller diameter to multiple small impeller diameters, converting the pump hydraulic from a low specific speed to a high specific speed to improve the efficiency. However, due to the large number of impellers, the pump occupies a large space, and there is a risk of leakage in multi-stage impellers. To reduce the motor temperature, a water-cooled jacket is used outside the stator of the canned motor. The disadvantage of this scheme is that more pipelines need to be configured on site, sufficient cooling water sources need to be prepared on site, and the cooling water pipelines need to be descaled regularly, resulting in higher equipment maintenance costs. Summary of the Utility Model

[0005] The main purpose of the utility model is to provide a small-flow canned pump, which can effectively solve the problems mentioned in the background technique.

[0006] To achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0007] A small-flow canned motor pump, comprising a motor housing, inside which a motor stator and a rotor assembly are assembled. At the front end of the motor housing, a pump body assembly is assembled. At the tail of the motor housing, a blower cover is additionally installed. Inside the blower cover, a blower impeller assembly is rotatably installed. At the front end of the blower impeller assembly, an external magnetic coupler is installed. At the corresponding position at the tail of the rotor assembly, an internal magnetic coupler is installed. A magnetic drive is formed between the internal magnetic coupler and the external magnetic coupler to drive the blower impeller assembly to rotate for dissipating heat from the motor housing.

[0008] Preferably, at the front end of the motor housing, a front motor cover is fixedly installed. The pump body assembly is fixedly installed on the front motor cover through bolts, and a front bearing body is installed between the pump body assembly and the front motor cover. At the front end of the front bearing body, a cover plate is installed. The rotor assembly passes through the front bearing body and extends into the pump body assembly, and the front bearing body and the rotor assembly are rotationally connected through a sliding bush and a sliding bearing sleeve.

[0009] Preferably, inside the pump body assembly, a full-open impeller assembly is provided. The impeller assembly is composed of an impeller hub and blades. The blades adopt a straight blade structure and are fixedly installed on the impeller hub. The impeller hub is fixedly installed at the front end of the rotor assembly. At the front end of the impeller assembly, a spiral inducer is also fixedly installed.

[0010] Preferably, the rotor assembly passes through the center of the motor stator, and a stator shield sleeve is provided between the motor stator and the rotor assembly. On the motor housing, a motor terminal box assembly is also provided, and the motor terminal box assembly is electrically connected to the motor stator.

[0011] Preferably, at the rear end of the motor housing, a rear motor cover is fixedly installed. At the outer end of the rear motor cover, a rear bearing body is fixedly installed. A circle of stator shield plates is additionally installed between the rear bearing body and the rear motor cover. At the tail of the rotor assembly, an auxiliary impeller for accelerating the internal circulation is installed, and the tail of the rotor assembly and the rear bearing body are also rotationally connected through a sliding bush and a sliding bearing sleeve.

[0012] Preferably, the tail end of the rotor assembly extends into the protruding part of the rear bearing body, and the internal magnetic coupler is annularly and fixedly installed.

[0013] Preferably, the external magnetic coupler is fixedly installed through bolts on the inner circle at the front end of the blower impeller assembly. The external magnetic coupler wraps around the outside of the protruding part of the rear bearing body and corresponds to the internal magnetic coupler.

[0014] Preferably, a deep groove ball bearing is fixedly installed at the center of the inner wall of the fan cover through a bearing gland. The tail of the fan impeller assembly is engaged with the outer ring of the deep groove ball bearing and is clamped and fixed by a positioning sleeve.

[0015] Preferably, the wind generated by the rotation of the fan impeller assembly blows from the tail to the head of the motor housing. A number of rib plates are longitudinally installed on the surface of the motor housing, and an air-cooling flow channel is formed between adjacent rib plates.

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] In the utility model, firstly, the main circulation hydraulics of the canned motor pump adopts the hydraulics design of a tangential pump. The impeller is of a fully open type and has a gap with the pump body and the pump cover. Part of the medium enters the diffuser section along the tangent. The straight blade design makes the head of the tangential pump higher under the same impeller diameter, and the efficiency is also higher than that of the centrifugal pump at low specific speed and small flow rate. Secondly, the internal circulation adopts a high-pressure circulation. The auxiliary impeller installed at the tail of the rotor assembly re-presses the circulating medium, and the internal circulation medium is always in a high-pressure state circulation, avoiding the decrease of the medium viscosity caused by the increase of the temperature of the internal circulation medium. Finally, by assembling a fan cover and a fan impeller assembly at the tail of the canned motor pump, a push-pull force coupling is formed by using a magnetic coupling, so that the fan impeller assembly is driven to rotate by the rotor assembly. The normal-temperature air is pressurized and forced to circulate through this, and the outer surface of the motor housing is cooled to ensure the long-term stable operation of the canned motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a sectional view of the overall structure of the utility model;

[0019] Figure 2 is a schematic diagram of the structure of the motor housing of the utility model;

[0020] Figure 3 is a schematic diagram of the structure of the impeller assembly of the utility model;

[0021] Figure 4 is a schematic diagram of the structure of the inducer of the utility model;

[0022] Figure 5 is a schematic diagram of the main circulation of the canned motor pump of the utility model;

[0023] Figure 6 is a schematic diagram of the internal circulation of the canned motor pump of the utility model;

[0024] Figure 7 is a schematic diagram of the air-cooling circulation of the canned motor pump of the utility model.

[0025] In the figure: 1. Impeller assembly; 2. Pump body assembly; 3. Front bearing housing; 4. Front motor cover; 5. Stator shield sleeve; 6. Motor stator; 7. Motor junction box assembly; 8. Fan cover; 9. Fan impeller assembly; 10. Bearing gland; 11. Deep groove ball bearing; 12. Inducer; 13. Cover plate; 14. Sleeve bearing; 15. Sleeve for sliding bearing; 16. Motor housing; 17. Rotor assembly; 18. Auxiliary impeller; 19. Rear motor cover; 20. Stator shield plate; 21. Rear bearing housing; 22. Inner magnetic coupler; 23. Outer magnetic coupler; 24. Positioning sleeve; 25. Rib plate; 26. Air-cooling channel; 27. Impeller hub; 28. Blade. Detailed implementation manners

[0026] In order to make the technical means, creative features, achieved purposes and functions of the present utility model easy to understand, the present utility model will be further described below in conjunction with the specific implementation manners.

[0027] As Figure 1 shown, a small-flow canned motor pump, its basic structure includes a motor housing 16, a front motor cover 4 is fixedly installed at the front end of the motor housing 16, a pump body assembly 2 is fixedly installed on the front motor cover 4 by bolts, and a front bearing housing 3 is installed between the pump body assembly 2 and the front motor cover 4. A cover plate 13 is installed at the front end of the front bearing housing 3. The rotor assembly 17 passes through the front bearing housing 3 and extends into the pump body assembly 2, and the front bearing housing 3 and the rotor assembly 17 are rotatably connected through a sleeve bearing 14 and a sleeve for sliding bearing 15; the rotor assembly 17 passes through the center of the motor stator 6, and a stator shield sleeve 5 is provided between the motor stator 6 and the rotor assembly 17. A motor junction box assembly 7 is also provided on the motor housing 16, and the motor junction box assembly 7 is electrically connected to the motor stator 6.

[0028] As Figure 1 、 Figure 3 、 Figure 4 、 Figure 5As shown, there is a fully open impeller assembly 1 inside the pump body assembly 2. The impeller assembly 1 is composed of an impeller hub 27 and blades 28. The blades 28 adopt a straight blade structure and are fixedly installed on the impeller hub 27. The impeller hub 27 is fixedly installed at the front end of the rotor assembly 17. A spiral inducer 12 is also fixedly installed at the front end of the impeller assembly 1. Among them, the main circulation hydraulics adopts the tangential pump hydraulic design method. Its principle is that the impeller assembly 1 adopts a fully open design, and there is a certain gap between the impeller assembly 1, the pump body assembly 2 and the cover plate 13. The medium rotates in the inner circle of the pressure water chamber of the pump body assembly 2, and only part of it enters the diffuser section along the tangent direction of the flow path. Its characteristics are that the gap between the impeller assembly 1, the pump body assembly 2 and the cover plate 13 is 0.5 - 1 mm, which has almost no influence on the pump performance. The impeller assembly 1 and the pump body assembly 2 are all completed by machining, and the surface roughness of the flow path can be strictly controlled, thereby reducing the disc loss friction and improving the hydraulic efficiency. Especially in the small flow condition, the disc loss friction can be reduced to the lowest. Since the blades 28 adopt straight blades, for the same impeller diameter, the head of the tangential pump impeller is higher than that of the centrifugal pump impeller. In the low specific speed and small flow conditions, the hydraulic efficiency of the tangential pump is higher than that of the centrifugal pump. The blades 28 are processed by wire cutting, and the impeller hub 27 is processed by forging (the material of the blades 28 can be selected as CD4MCu, 2205 or Hastelloy to improve the corrosion resistance and wear resistance of the impeller assembly 1). The outlet edge of the blades 28 needs to be hand-polished and chamfered to increase the outlet area and thus increase the head, and the inlet edge of the blades 28 needs to be hand-polished and chamfered to increase the inlet flow area and thus reduce the cavitation margin of the impeller. The blades 28 and the impeller hub 27 are welded into a whole. Finish machining is carried out after welding. Because the straight blades are adopted for the hydraulics, the cavitation margin of the tangential pump hydraulics is usually relatively high. An inducer 12 can be added at the impeller inlet to increase the medium pressure at the impeller inlet, thereby reducing the cavitation margin of the whole pump.

[0029] In addition, such as Figure 1 , Figure 6As shown in the figure, an auxiliary impeller 18 for accelerating the internal circulation is installed at the tail of the rotor assembly 17, and the tail of the rotor assembly 17 is also rotatably connected to the rear bearing housing 21 through a sliding bushing 14 and a sliding bearing sleeve 15; a part of the medium in the main circulation is diverted when flowing out of the outlet of the pump body assembly 2, passes through the circulation holes on the front bearing housing 3 and the cover plate 13, enters the rear cavity of the rotor, and enters the auxiliary impeller 18 through the hollow shaft on the rotor assembly 17. This part of the circulating medium is pressurized again by the auxiliary impeller 18. A small part circulates backward to lubricate the sliding bushing 14 and the sliding bearing sleeve 15, and a large part takes away the heat generated by the motor through the gap between the outer surface of the rotor assembly 17 and the inner surface of the stator shielding sleeve 5. This part of the internal circulating medium with a certain temperature rise merges with the main circulation through the circulation holes on the front bearing housing 3 and the cover plate 13 and flows out of the pump body assembly 2. The internal circulating medium is always in a high-pressure state, which can ensure that the temperature of the internal circulating medium does not rise, resulting in a decrease in the viscosity of the medium, and further causing insufficient lubrication of the sliding bearing and damage.

[0030] As Figure 1 , Figure 2 , Figure 7 As shown in the figure, a rear motor cover 19 is fixedly installed at the rear end of the motor housing 16, and a rear bearing housing 21 is fixedly installed at the outer end of the rear motor cover 19. A ring of stator shielding plates 20 is also installed between the rear bearing housing 21 and the rear motor cover 19. The tail end of the rotor assembly 17 extends into the protruding part of the rear bearing housing 21, and an internal magnetic coupler 22 is fixedly installed annularly. The inner ring at the front end of the fan impeller assembly 9 is fixedly installed with an external magnetic coupler 23 through bolts. The external magnetic coupler 23 is wrapped outside the protruding part of the rear bearing housing 21 and corresponds to the internal magnetic coupler 22. A deep groove ball bearing 11 is fixedly installed at the center of the inner wall of the fan cover 8 through a bearing gland 10. The tail of the fan impeller assembly 9 is clamped on the outer ring of the deep groove ball bearing 11 and is clamped and fixed through a positioning sleeve 24. The wind generated by the rotation of the fan impeller assembly 9 blows from the tail to the head of the motor housing 16. A number of rib plates 25 are longitudinally installed on the surface of the motor housing 16, and an air-cooling flow channel 26 is formed between adjacent rib plates 25.

[0031] In actual work, the fan impeller assembly 9 is supported by a maintenance-free deep groove ball bearing 11 with grease. When the rotor assembly 17 rotates, it naturally drives the inner magnetic coupler 22 to rotate. Through the magnetic coupling effect, it naturally drives the outer magnetic coupler 23 to rotate. The outer magnetic coupler 23 is fixedly connected to the fan impeller assembly 9. Therefore, the fan impeller assembly 9 is synchronously driven to rotate. Normal temperature air enters the fan impeller assembly 9 through the end face holes of the fan cover 8, is pressurized by the fan impeller assembly 9 and forced to circulate to cool the outer surface of the motor housing 16. The heat generated by the motor stator is quickly transferred to the outer surface of the motor housing 16 due to heat transfer. At the same time, because the small flow rate canned motor pump is equipped with an air-cooled cycle, the wall thickness of the motor housing 16 is designed to be relatively thin, usually 3-4 mm. Therefore, rib plates 25 are designed on the surface of the motor housing 16 to ensure strength. The rib plates 25 not only ensure sufficient rigidity of the motor housing 16 but also increase the outer surface area of the motor housing 16, increase the heat transfer area, improve the heat transfer efficiency, and also form an air-cooled flow channel 26 to ensure that the air-cooled cycle can reduce the temperature of the canned motor stator from 70-80 °C to below 50 °C. Since part of the heat of the motor is cooled by air cooling, the temperature of the internal circulation is relatively low, ensuring that the canned motor can operate stably for a long time and avoiding damage to the small flow rate canned motor pump caused by high temperature vaporization of the internal circulation.

[0032] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A small flow canned motor pump, comprising a motor housing (16), wherein a motor stator (6) and a rotor assembly (17) are assembled inside the motor housing (16), and a pump assembly (2) is assembled at the front end of the motor housing (16), characterized in that: A fan cover (8) is additionally installed at the rear of the motor outer shell (16); a fan impeller assembly (9) is rotatably installed on the inner wall of the fan cover (8); an external magnetic coupler (23) is installed at the front end of the fan impeller assembly (9); and an internal magnetic coupler (22) is correspondingly installed at the rear of the rotor assembly (17); a magnetic drive is formed between the internal magnetic coupler (22) and the external magnetic coupler (23), driving the fan impeller assembly (9) to rotate to dissipate heat for the motor outer shell (16).

2. A small flow canned motor pump according to claim 1, characterized in that: A front motor cover (4) is fixedly mounted on the front end of the motor housing (16); the pump body assembly (2) is fixedly mounted on the front motor cover (4) by means of bolts; a front bearing body (3) is mounted between the pump body assembly (2) and the front motor cover (4); a cover plate (13) is mounted on the front end of the front bearing body (3); the rotor assembly (17) passes through the front bearing body (3) and extends into the pump body assembly (2); and the front bearing body (3) and the rotor assembly (17) are rotatably connected via a sliding bushing (14) and a sliding bearing sleeve (15).

3. A small flow canned motor pump according to claim 2, characterized in that: A fully open impeller assembly (1) is provided inside the pump body assembly (2). The impeller assembly (1) is composed of an impeller hub (27) and blades (28). The blades (28) are of a straight blade structure and are fixedly mounted on the impeller hub (27). The impeller hub (27) is fixedly mounted to the front end of the rotor assembly (17). A spiral inducer (12) is also fixedly mounted on the front end of the impeller assembly (1).

4. A small flow canned motor pump according to claim 1, characterized in that: The rotor assembly (17) passes through the center of the motor stator (6), and a stator shielding sleeve (5) is located between the motor stator (6) and the rotor assembly (17). A motor terminal box assembly (7) is also provided on the motor outer shell (16), and the motor terminal box assembly (7) is electrically connected to the motor stator (6).

5. A small flow canned motor pump according to claim 2, characterized in that: A rear motor cover (19) is fixedly mounted at the rear end of the motor outer shell (16), and a rear bearing body (21) is fixedly mounted at the outer end of the rear motor cover (19). A stator shielding plate (20) is additionally installed between the rear bearing body (21) and the rear motor cover (19). An auxiliary impeller (18) for accelerating internal circulation is installed at the tail of the rotor assembly (17), and the tail of the rotor assembly (17) and the rear bearing body (21) are also rotatably connected via a sliding bushing (14) and a sliding bearing sleeve (15).

6. A small flow canned motor pump according to claim 5, characterized in that: The tail end of the rotor assembly (17) extends into the interior of the protruding portion of the rear bearing body (21), and an inner magnetic coupler (22) is fixedly installed in an annular shape.

7. A small flow canned motor pump according to claim 6, characterized in that: An external magnetic coupler (23) is fixedly mounted on the front inner ring of the fan impeller assembly (9) by means of bolts. The external magnetic coupler (23) is wrapped around the outside of the protruding part of the rear bearing body (21) and corresponds to the internal magnetic coupler (22).

8. A small flow canned motor pump according to claim 7, characterized in that: A deep groove ball bearing (11) is fixedly mounted at the center of the inner wall of the fan cover (8) via a bearing cover (10), and the tail of the fan impeller assembly (9) is engaged with the outer ring of the deep groove ball bearing (11) and is clamped and fixed by a positioning sleeve (24).

9. A small flow canned motor pump according to claim 8, characterized in that: The wind generated by the rotation of the fan impeller assembly (9) is blown from the rear end of the motor outer shell (16) to the head end. A plurality of ribs (25) are longitudinally mounted on the surface of the motor outer shell (16), and air cooling channels (26) are formed between adjacent ribs (25).

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