A rotational speed measuring device for a canned motor pump unit

Abstract

The present invention discloses a rotational speed measuring device for a canned motor pump set, which includes a shaft head connecting rod, an exhaust valve connecting pipe, an exhaust valve, a sensor bracket and a rotational speed sensor. A threaded hole is provided at the tail of the motor rotor shaft of the pump set, and the head of the shaft head connecting rod is threadedly connected to the threaded hole at the tail of the motor rotor shaft; a blind hole is provided at the tail of the shaft head connecting rod, and an internal magnet is embedded in the blind hole, and the opening end of the blind hole is welded and sealed; the lower end of the exhaust valve connecting pipe is threadedly connected to the exhaust hole on the motor top cover and is sealed by a sealing gasket, and the upper end of the exhaust valve connecting pipe is connected to the exhaust valve; the rotational speed sensor is adjacent to the exhaust valve connecting pipe, and the rotational speed sensor is used to detect the rotational speed of the internal magnet. The rotational speed measuring device for the canned motor pump set of the present invention makes the rotational speed measurement of the pump set convenient and safe; it is not only convenient for maintenance and disassembly, but also can reduce the number of openings on the pump set and reduce the leakage risk of the pump set.

Description

Technical Field

[0001] The present invention relates to a rotational speed measuring device for a canned motor pump unit. Background Art

[0002] Canned motor pump units are mostly used for transporting toxic and harmful media, and have relatively high requirements for the safety and reliability of the pump unit. Real-time monitoring of the rotational speed of the pump unit has important safety significance.

[0003] For ordinary centrifugal pump units, a light-sensitive film is usually set on the pump shaft, and the rotational speed of the shaft is determined by detecting the rotational speed of the light-sensitive film. The canned motor pump unit is a fully sealed pump, and a light-sensitive element cannot be installed on the pump shaft. There is also a structure in which a hole is opened on the pump body or the pump cover, and a sensor is inserted into the pump body to measure the rotational speed of the pump unit. This method increases the number of holes in the pump unit and increases the leakage risk. Therefore, in view of the above drawbacks, it is necessary to design a new rotational speed measurement method to make the rotational speed measurement of the pump unit convenient and not affect the safety and reliability of the pump unit. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a rotational speed measuring device for a canned motor pump unit, which makes the rotational speed measurement of the pump unit convenient and safe; is not only convenient for maintenance, disassembly and assembly, but also can reduce the number of holes on the pump unit and reduce the leakage risk of the pump unit.

[0005] The technical solution for realizing the above purpose is: a rotational speed measuring device for a canned motor pump unit, which is installed on the motor top cover of the pump unit. An exhaust hole penetrating up and down is opened on the motor top cover. The rotational speed measuring device includes a shaft head connecting rod, an exhaust valve connecting pipe, an exhaust valve, a sensor bracket and a rotational speed sensor, wherein:

[0006] A threaded hole is opened at the tail of the motor rotor shaft of the pump unit. The head of the shaft head connecting rod is threadedly connected in the threaded hole at the tail of the motor rotor shaft and is fastened on the motor rotor shaft by tightening a nut. The shaft head connecting rod rotates together with the motor rotor shaft.

[0007] A blind hole is opened at the tail of the shaft head connecting rod. An internal magnet is embedded in the blind hole, and the opening end of the blind hole is welded and sealed.

[0008] The lower end of the exhaust valve connecting pipe is threadedly connected in the exhaust hole on the motor top cover and is sealed by a sealing gasket. The upper end of the exhaust valve connecting pipe is connected to the exhaust valve.

[0009] The tail of the shaft head connecting rod passes through the exhaust hole on the motor top cover and is inserted into the exhaust valve connecting pipe. A water guide bearing is arranged between the middle part of the shaft head connecting rod and the exhaust hole, and a snap ring is installed at the top end of the water guide bearing.

[0010] The sensor bracket is L-shaped. The horizontal part of the sensor bracket is fixed to the top end of the motor top cover through fastening bolts, and the rotational speed sensor is horizontally arranged on the vertical part of the sensor bracket through a lock nut;

[0011] The rotational speed sensor is adjacent to the exhaust valve connection pipe, and the rotational speed sensor is used to detect the rotational speed of the built-in magnetic steel;

[0012] A water return hole communicating with the exhaust hole is also provided on the motor top cover.

[0013] In the above rotational speed measuring device for a canned motor pump unit, the inner wall surface of the water guide bearing is provided with spiral grooves, and the rotation angle of the spiral grooves is 45 - 60°.

[0014] In the above rotational speed measuring device for a canned motor pump unit, the exhaust hole on the motor top cover is composed of a sealing gasket installation section, an exhaust valve connection pipe installation section, a snap ring installation section, a water guide bearing installation section, and a shaft head connecting rod insertion section that are coaxially connected in sequence from top to bottom, and the inner diameters of the sealing gasket installation section, the exhaust valve connection pipe installation section, the snap ring installation section, the water guide bearing installation section, and the shaft head connecting rod insertion section decrease in sequence;

[0015] The sealing gasket is arranged in the sealing gasket installation section;

[0016] The lower end of the exhaust valve connection pipe passes through the sealing gasket and is threadedly connected in the exhaust valve connection pipe installation section;

[0017] The snap ring is arranged in the snap ring installation section;

[0018] The water guide bearing is located in the water guide bearing installation section;

[0019] The tail of the shaft head connecting rod sequentially passes through the shaft head connecting rod insertion section, the water guide bearing, the snap ring, and the lower end of the exhaust valve connection pipe and then inserts into the exhaust valve connection pipe;

[0020] There is a first gap between the outer wall surface of the shaft head connecting rod and the inner wall surface of the shaft head connecting rod insertion section of the exhaust hole, a second gap between the inner wall surface of the water guide bearing and the outer wall surface of the shaft head connecting rod, a third gap between the inner wall surface of the exhaust valve connection pipe and the outer wall surface of the shaft head connecting rod, and a fourth gap between the rotational speed sensor and the outer wall surface of the exhaust valve connection pipe.

[0021] In the above rotational speed measuring device for a canned motor pump unit, the diameter of the water return hole is 5 mm - 6 mm; the water return hole includes an inclined section and a vertical section connected thereto, and the inclined section of the water return hole is connected to the exhaust hole.

[0022] The rotational speed measuring device for a canned motor pump set of the present invention enables convenient and safe measurement of the rotational speed of the pump set; it is not only convenient for maintenance, disassembly and assembly, but also can reduce the number of openings on the pump set and the leakage risk of the pump set. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the rotational speed measuring device for a canned motor pump set of the present invention;

[0024] Figure 2 is a schematic structural diagram of the shaft head connecting rod;

[0025] Figure 3 is a cross-sectional view of the water guide bearing;

[0026] Figure 4 is a schematic structural diagram of the exhaust hole and the return water hole on the motor top cover;

[0027] Figure 5 is Figure 1 a partial enlarged view of part A in

[0028] Figure 6 is a schematic installation diagram of the rotational speed sensor. DETAILED DESCRIPTION OF THE INVENTION

[0029] In order to enable those skilled in the art of the present technology to better understand the technical solution of the present invention, the following detailed description of its specific implementation manner is provided in conjunction with the accompanying drawings:

[0030] Please refer to Figures 1 to 6 , the best embodiment of the present invention, a rotational speed measuring device for a canned motor pump set, is installed on the motor top cover 4 of the pump set. An exhaust hole 41 penetrating up and down and a return water hole 42 communicating with the exhaust hole are provided on the motor top cover 4 (see Figure 4 ). The rotational speed measuring device includes a shaft head connecting rod 3, an exhaust valve connecting pipe 8, an exhaust valve 9, a sensor support 12, and a rotational speed sensor 10.

[0031] A threaded hole is provided at the tail 1 of the motor rotor shaft of the pump set. The head of the shaft head connecting rod 3 is provided with a mounting thread 31. The head of the shaft head connecting rod 3 is threadedly connected to the threaded hole at the tail 1 of the motor rotor shaft and is fastened to the motor rotor shaft by tightening a nut 2. The shaft head connecting rod 3 rotates together with the motor rotor shaft; a blind hole is provided at the tail of the shaft head connecting rod 3, and an internal magnet 32 is embedded in the blind hole, and the open end of the blind hole is welded and sealed 33 (see Figure 2 ).

[0032] The lower end of the exhaust valve connection pipe 8 is threadedly connected to the exhaust hole 41 on the motor top cover 4 and sealed by a sealing gasket 6. The upper end of the exhaust valve connection pipe 8 is connected to the exhaust valve 9. The tail of the shaft head connecting rod 3 passes through the exhaust hole 41 on the motor top cover and is inserted into the exhaust valve connection pipe 8. A water guide bearing 5 is arranged between the middle of the shaft head connecting rod 3 and the exhaust hole 41. A circlip 7 is installed at the top end of the water guide bearing 5 to prevent the water guide bearing 5 from loosening during long-term operation.

[0033] The sensor bracket 12 is L-shaped. The horizontal part of the sensor bracket 12 is fixed to the top end of the motor top cover 4 by fastening bolts 13. The rotational speed sensor 10 is horizontally arranged on the vertical part of the sensor bracket 12 through a lock nut 11. The rotational speed sensor 10 is adjacent to the exhaust valve connection pipe 8. The rotational speed sensor 10 is used to detect the rotational speed of the built-in magnetic steel 33, and thus detect the rotational speed of the canned motor pump set.

[0034] To prevent the shaft head connecting rod 3 from having too large a deflection when rotating with the pump, a water guide bearing 5 is embedded in the exhaust hole 41 of the motor top cover. Please refer to Figure 3 again. To prevent the water guide bearing 5 from getting hot during long-term operation, spiral grooves 51 are machined on the inner wall surface of the water guide bearing 5. The rotation angle of the spiral grooves 51 is 45 - 60°. The rotation direction of the spiral grooves 51 is conducive to the medium moving upward along the grooves and returning to the motor cavity through the water return hole 42 on the motor top cover 4.

[0035] Please refer to Figure 4 again. The exhaust hole 41 on the motor top cover 4 is composed of a sealing gasket installation section 411, an exhaust valve connection pipe installation section 412, a circlip installation section 413, a water guide bearing installation section 414, and a shaft head connecting rod insertion section 415 that are coaxially connected in sequence from top to bottom. The inner diameters of the sealing gasket installation section 411, the exhaust valve connection pipe installation section 412, the circlip installation section 413, the water guide bearing installation section 414, and the shaft head connecting rod insertion section 415 decrease in sequence. The diameter of the water return hole 42 is 5 mm - 6 mm; the water return hole 42 includes an inclined section 421 and a vertical section 422 connected thereto. The inclined section 421 of the water return hole 42 is connected to the exhaust valve connection pipe installation section 412 of the exhaust hole 41. To facilitate the machining of the water return hole on the top cover, the angle a1 of the inclined section 421 of the water return hole 42 can be set according to the structure.

[0036] For the rotational speed measuring device for the canned motor pump set of the present invention, the sealing gasket 6 is arranged in the sealing gasket installation section 411; the lower end of the exhaust valve connection pipe 8 passes through the sealing gasket 6 and is threadedly connected to the exhaust valve connection pipe installation section 412; the circlip 7 is arranged in the circlip installation section 413; the water guide bearing 5 is located in the water guide bearing installation section 414; the tail of the shaft head connecting rod 3 passes through the shaft head connecting rod insertion section 415, the water guide bearing 5, the circlip 7, and the lower end of the exhaust valve connection pipe 8 in sequence and then is inserted into the exhaust valve connection pipe 8.

[0037] Please refer to again Figure 5 and Figure 6 There is a first gap d1 between the outer wall surface of the shaft head connecting rod 3 and the inner wall surface of the shaft head connecting rod insertion section 415 of the exhaust hole 41. There is a second gap d2 between the inner wall surface of the water guide bearing 5 and the outer wall surface of the shaft head connecting rod 3. There is a third gap d3 between the inner wall surface of the exhaust valve connection pipe 8 and the outer wall surface of the shaft head connecting rod 3. Before the pump unit starts, the pump unit needs to be exhausted. The gas in the upper part of the motor enters the second gap d2 between the water guide bearing and the shaft head connecting rod and the groove width gap r1 of the spiral groove through the first gap d1 between the shaft head connecting rod 3 and the exhaust hole 41 of the motor top cover, and then enters the exhaust valve 9 through the third gap d3 between the exhaust valve connection pipe 8 and the shaft head connecting rod 3. Since the second gap d2 between the water guide bearing 5 and the shaft head connecting rod 3 is small, the exhaust efficiency of the pump unit is reduced, and it can be compensated exactly through the water return hole 42 on the motor top cover 4.

[0038] There is a fourth gap d4 between the speed sensor 10 and the outer wall surface of the exhaust valve connection pipe 8. The width of the fourth gap d4 is determined according to the magnetic induction type, sensor type and the thickness of the exhaust valve connection pipe, and it is necessary to ensure that the speed sensor 10 does not collide with the exhaust valve connection pipe 8 due to the vibration of the pump unit during the operation of the pump unit.

[0039] For the speed measurement device for the canned motor pump unit of the present invention, when in use, an internal magnet 32 is arranged at the tail of the shaft head connecting rod 3. The tail of the shaft head connecting rod 3 is located inside the exhaust valve connection pipe 8. The shaft head connecting rod 3 rotates together with the motor rotor shaft. The rotation speed of the internal magnet 32 in the shaft head connecting rod 3 is detected by the speed sensor 20 installed on the motor top cover 4, and then the rotation of the pump unit is determined.

[0040] The speed measurement device for the canned motor pump unit of the present invention utilizes the exhaust structure of the pump unit itself, without the need to additionally process measurement holes on the pump unit, reducing the leakage risk, and the speed sensor is external, which is convenient for disassembly, installation and maintenance. When the speed sensor 10 is removed, the internal shaft head connecting rod 3 does not need to be removed, which does not affect the performance of the pump unit. The setting of the water guide bearing 5 can improve the rotation stability of the shaft head connecting rod 3 and prevent excessive working deflection from causing rubbing. The setting of the water return hole 42 can compensate for the adverse effects such as difficult exhaust caused by the too small second gap d2.

[0041] In summary, the speed measurement device for the canned motor pump unit of the present invention is particularly suitable for the speed measurement of canned motor pump units for transporting high-pressure media and toxic and harmful media, making the speed measurement of the pump unit convenient and safe; it is not only convenient for maintenance, disassembly and installation, but also can reduce the number of holes on the pump unit and reduce the leakage risk of the pump unit.

[0042] Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. As long as they are within the spirit of the present invention, changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A rotational speed measuring device for a canned motor pump set, which is installed on the motor top cover of the pump set, and an exhaust hole penetrating up and down is opened on the motor top cover, and is characterized in that, The rotation speed measuring device includes a shaft head connecting rod, an exhaust valve connecting pipe, an exhaust valve, a sensor bracket and a rotation speed sensor, where: A threaded hole is provided at the tail of the motor rotor shaft of the pump set. The head of the shaft head connecting rod is threadedly connected to the threaded hole at the tail of the motor rotor shaft and is fastened to the motor rotor shaft by tightening a nut. The shaft head connecting rod rotates together with the motor rotor shaft. A blind hole is provided at the tail of the shaft head connecting rod. A built-in magnetic steel is embedded in the blind hole, and the opening end of the blind hole is welded and sealed. The lower end of the exhaust valve connecting pipe is threadedly connected to the exhaust hole on the motor top cover and is sealed by a sealing gasket. The upper end of the exhaust valve connecting pipe is connected to the exhaust valve. The tail of the shaft head connecting rod passes through the exhaust hole on the motor top cover and is inserted into the exhaust valve connecting pipe. A water guide bearing is provided between the middle of the shaft head connecting rod and the exhaust hole, and a circlip is installed at the top end of the water guide bearing. The sensor bracket is L-shaped. The horizontal part of the sensor bracket is fixed to the top end of the motor top cover by fastening bolts. The rotation speed sensor is horizontally arranged on the vertical part of the sensor bracket through a lock nut. The rotation speed sensor is adjacent to the exhaust valve connecting pipe, and the rotation speed sensor is used to detect the rotation speed of the built-in magnetic steel. A return water hole communicating with the exhaust hole is also provided on the motor top cover.

2. The rotational speed measuring device for a canned motor pump set according to claim 1, characterized in that, A spiral groove is provided on the inner wall surface of the water guide bearing, and the rotation angle of the spiral groove is 45° to 60°.

3. The rotational speed measuring device for a canned motor pump set according to claim 1, characterized in that, The exhaust hole on the motor top cover is composed of a sealing gasket installation section, an exhaust valve connecting pipe installation section, a circlip installation section, a water guide bearing installation section and a shaft head connecting rod insertion section that are coaxially connected in sequence from top to bottom. The inner diameters of the sealing gasket installation section, the exhaust valve connecting pipe installation section, the circlip installation section, the water guide bearing installation section and the shaft head connecting rod insertion section decrease in sequence. The sealing gasket is arranged in the sealing gasket installation section. The lower end of the exhaust valve connecting pipe passes through the sealing gasket and is then threadedly connected to the exhaust valve connecting pipe installation section. The circlip is arranged in the circlip installation section. The water guide bearing is located in the water guide bearing installation section. The tail of the shaft head connecting rod sequentially passes through the shaft head connecting rod insertion section, the water guide bearing, the circlip and the lower end of the exhaust valve connecting pipe and then is inserted into the exhaust valve connecting pipe. There is a first gap between the outer wall surface of the shaft head connecting rod and the inner wall surface of the shaft head connecting rod insertion section of the exhaust hole. There is a second gap between the inner wall surface of the water guide bearing and the outer wall surface of the shaft head connecting rod. There is a third gap between the inner wall surface of the exhaust valve connecting pipe and the outer wall surface of the shaft head connecting rod. There is a fourth gap between the rotation speed sensor and the outer wall surface of the exhaust valve connecting pipe.

4. A rotational speed measuring device for a canned motor pump set according to claim 1, characterized in that, The diameter of the return water hole is 5 mm to 6 mm. The return water hole includes an inclined section and a vertical section connected thereto. The inclined section of the return water hole is connected to the exhaust hole.

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