JPS6111518Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the shape of the shaft end and hub of the impeller attachment portion of the pump shaft.

Conventionally, when installing an impeller at the tip of the pump main shaft, the shaft end was made cylindrical, a keyway was carved along the cylindrical generatrix, the key was inserted, and the hub center hole of the impeller was also aligned with the cylindrical shaft. Fit the hub as a cylindrical hub with a keyway, cut a thread on the outer diameter of the pump shaft end or the center of the pump shaft end surface, screw the impeller set screw in the axial direction, and connect the impeller hub to the end of the pump shaft. A frequently used stopping method is to press against the stepped portion to stop the axial movement. However, when such a key is used as a means for transmitting torque from the pump shaft to the impeller, the following problems arise. (1) Due to the loss of the key, the shaft diameter must be increased in consideration of stress concentration. (2) The hub diameter must be increased in consideration of stress concentration at the corner of the key of the impeller hub. (3) Therefore, the pump shaft mounting portion of the impeller becomes large. (4) Machining of the key on the pump shaft side is performed using an end mill, a vertical milling machine, or a special key seater machine, but the machining is difficult and it is difficult to set the key correctly around the keyway. Therefore, in machining, it is necessary to use end mills separately to perform finish cutting on both sides of the keyway. (5) Due to the design, the impeller boss and pump shaft end must be made longer to accommodate the required length of the key. (6) When automatically assembling the impeller to the pump shaft, insert the key into the keyway of the pump shaft. Two steps are required: inserting the impeller bore into the pump shaft containing the key, and each step is extremely difficult to assemble automatically. (7) When disassembling the pump, the impeller must be removed from the pump shaft and the key at the end of the pump shaft must be removed first as it will interfere with the shaft sealing device, but the key is firmly pressed into the pump shaft and keyway. In some cases, stress corrosion occurs due to use, making it difficult to remove the key. (8) Even when assembled, there are no keys in the keyway portions at both ends of the impeller hub, resulting in unbalanced weight. There are other problems.

In order to solve the problem of attaching the impeller to the pump shaft with a key, a spline can be carved on the end of the pump shaft, and a female spline can also be carved on the impeller hub and fitted, but the spline machining is not suitable for the pump shaft. If indexing and cutting is performed using a full-form spline cutter, or cutting is performed using a spline hob and then hardened, spline grinding is further performed. In machining these spline shafts, the tool interferes with the adjacent large diameter shaft, so it is necessary to make the shaft neck long. The hub of the impeller is broached. As described above, spline processing requires an extremely large amount of man-hours. Furthermore, when performing automatic assembly, spline fittings are not suitable for pump shafts and impellers, as fixing splines have small tolerances and gaps and are usually not hardened, unless the motion splines are hardened and ground. There is a risk of car damage. In terms of strength, the cross-sectional defect is large, and when stress concentration is taken into account, photoelastic experiment results show that the strength is equivalent to 0.707 times the valley diameter. Therefore, simply replacing the keyway with a spline leaves many problems.

There is a known example in which a square shaft is used to attach an impeller to a pump shaft (US Pat. No. 3,481,273). According to this known example, a food pump has a square hole formed in the impeller hub, the pump shaft has a square cross section, and the corners of the square shaft are rounded, and the pump hub can be assembled with the corners of the square hole raised. It is designed to create a passage, and generally a method of fitting a square shaft into a square hole is used.

When fitting a polygonal hole and a polygonal shaft as in the conventional method, the surfaces of each side are aligned and the corners on the shaft side are chamfered. With this method, eccentricity, inclination, etc. of the assembled impeller may occur depending on the machining accuracy of the shaft and hole sides. Therefore, it is necessary to machine the shaft hole extremely accurately. When machining polygonal objects, it is necessary to keep the distance from the axis to each side, the angular error between each side when equally distributed, the overall shape error, etc. within a certain range, but cylindrical machining It is particularly difficult to position the shaft, and the hole requires a high-precision broach, and the method of correcting the broach withdrawal is difficult and is prone to eccentricity.

This idea solves the problems of the conventional method of attaching an impeller to the pump shaft of the pump, increases the strength of the pump shaft, contributes to the miniaturization of the pump, and reduces the number of man-hours in machining. The objective is to obtain an inner peripheral shape of the pump shaft and impeller hub that is easy to disassemble and assemble, and is especially suitable for automatic assembly.

This idea involves forming the shaft neck of the impeller attachment part of the pump shaft and the hub hole of the impeller into polygonal parts with a polygonal cross section, and forming a circular cylinder with the corners of the polygonal parts as the center of the pump shaft axis. The cylindrical part of the shaft neck of the pump shaft and the cylindrical part of the hub hole of the impeller are the fitting parts for centering the pump shaft and the impeller, and the shaft neck of the pump shaft and the hub hole of the impeller are the fitting parts for centering the pump shaft and the impeller. The sides of the polygonal part are shaped to fit together with play, and the pump shaft and impeller are mounted in such a manner that the hub hole of the impeller is fitted into the shaft neck of the pump shaft.

Embodiments of this invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a submersible motor pump. An impeller 3 is fixed to the end of the pump main shaft 2 protruding into the pump casing 1, a strainer 4 is fixed to the suction port side of the pump casing 1, and the strainer 4 is discharged through a discharge pipe (not shown) connected to the discharge port 5. be done. A mechanical seal 7 is provided between the pump casing 1 and the motor frame 6 fixed thereto, and a rotor 9 is fixed to the pump main shaft 2 with a gap between it and a stator 8 fixed to the motor frame 6. The pump main shaft 2 is mounted on a motor cover 11 that is fitted and fixed to the motor frame 6 and bearings 12 and 13 that are mounted on the motor frame 6.

A watertight connector 1 is attached to the motor cover 11.
An underwater cable 15 is led through 4 and wired to the stator 8.

The pump main shaft 2 is similar to a normal electric motor above the lower bearing 13. The shaft neck of the bearing 13 is the bearing 13
The shaft seal part shaft neck 16 with a smaller diameter is located below the position of
The shaft neck protruding from the shaft seal into the pump casing 1 has the shape of the pump shaft of this invention.

FIG. 2 is a partially enlarged view of FIG. 1, showing the shaft seal and the attachment of the impeller to the pump shaft. The fixed liner ring 18 to which the sliding ring 17 is fixed is fitted with a sealing ring 19 on its outer periphery and fitted into the pump casing 1, and is prevented from axial escape by a retaining plate 22 fixed to the pump casing 1 with machine screws 21. , the inner diameter of the fixed liner ring 18 is inserted into the shaft neck 16 of the pump main shaft 2. The sliding ring 23 is fitted into the central boss portion of the motor frame 6, and a moving ring 25 made of an elastic body with a pair of sliding rings 24 fixed between the sliding rings 17 and 23 is pivoted to the shaft neck 16 of the pump main shaft 2. A spring 26 is compressed and inserted between the movable rings 25 and elastically presses the sliding ring 24 against the sliding rings 17 and 23 via the movable ring 25.

A step 27 is provided at the end of the shaft neck 16 of the pump main shaft 2 so that one end of the hub 28 of the impeller 3 can come into contact with the end, and the impeller is attached to the pump main shaft 2 so that the step 27 makes the shaft neck 16 thinner than the shaft neck 16. A shaft neck 29 is formed.

FIG. 3 is a side view showing the impeller mounting portion 29 of the pump main shaft 2, and FIG. 4 is a sectional view taken along line AA in FIG. A cylindrical portion 30 having a diameter equal to or smaller than the diameter of the shaft neck 16 is rounded to form a polygonal portion 31. The polygonal portion 31 has a surface width larger than the remaining width of the circumferential portion of the cylindrical portion 30 . In the embodiment, the shape is a regular hexagon, but the shape is not limited to a hexagon. Step 27
An relief groove 32 is provided on the circumference at the base of the hexagon so that the illustrated diameter d2 is smaller than the distance m between opposite sides of the hexagon. This clearance groove 32 is provided to facilitate machining of each side of the polygonal portion 31 and the insertion of the hub 28 of the impeller 3 (the hub 28 of the impeller 3 will be described later). The end of the cylindrical part 30 is the assembly introduction part 3
3 is provided. The assembly introduction part 33 is tapered, and the diameter d3 of the small end of the taper is smaller than the distance m between opposite sides of the polygonal part 31. An external thread 34 having a diameter smaller than the small end diameter d3 is cut from the introduction portion 33 that produces the small end diameter d3. Note that the introduction portion 33 may be provided with a stepped portion having a diameter smaller than the distance m between opposite sides.

FIG. 5 is a longitudinal sectional view of the hub 28 of the impeller 3.

FIG. 6 is a sectional view taken along line BB in FIG. 5. The hub hole of the hub 28 of the impeller 3 is located at the end surface 2 that abuts the stage 27.
A taper 33' is provided on the 7' side.
The diameter of the small end of the cylindrical part 3 that fits into the cylindrical part 30 is
equal to the diameter of 0'. A regular hexagonal polygonal portion 31' is provided so as to leave the cylindrical portion 30'. Introduction part 3
3. Tapers 33' are provided on both the shaft neck 29 of the impeller attachment portion of the pump main shaft 2 and the hub 28 of the impeller, but either one may be made larger and one may be omitted.

The dimensions of the cylindrical portions 30 and 30' are their diameters d1 and D.
1 fits the pump main shaft 2 and the impeller 3, so that the tolerance is within the range of fit or press fit with a small tightening allowance. That is, this part is a fitting part where the centering of the pump main shaft 2 and the impeller 3 is to be performed. The distances m and M between the opposite sides of the polygonal portions 31 and 31' are M-m/2, which is a size such that a gap will necessarily occur due to the fitting tolerance.

It is longer than the length of the shaft neck 29 of the raw kill impeller attachment part of the hub 28, and the impeller 3 is fastened to the external thread 34.
A nut 35 that presses toward 7 is screwed in.

When assembling the pump main shaft 2 and the impeller 3, first insert the hub hole of the hub 28 of the impeller 3, and then
3' to the introduction part 33 and move it in the axial direction while rotating the impeller 3 to separate the cylindrical part 30 and the polygonal part 31 of 30'.
The impeller 3 is inserted in the axial direction by finding a point where 31' and 31' coincide, and the end surface 27' of the hub is brought into contact with the step 27. These operations are performed manually or by automatic assembly.

FIG. 7 is an axis-perpendicular sectional view of the impeller mounting portion shaft neck 29 and hub 28 of the pump main shaft 2 assembled as described above. The cylindrical parts 30, 30' are in full contact with each other in the case of press fitting, and in part in the case of static fitting. If the polygonal portions 31 and 31' are inserted in parallel, a gap of δ shown in the figure will be created, but the probability of this is low and the polygonal portions will be tilted. In either case, since there is a shape error in the polygonal parts 31, 31', the gap between the opposing sides of the polygonal parts 31, 31' and the relative slopes of the sides differ in size.

When the impeller nut 35 is rotated or the pump is driven, the impeller 3 receives a load and if the cylindrical parts 30 and 30' are a tight fit, the impeller 3 rotates relative to the pump main shaft 2. As shown in FIG. 8, which is the same cross section as FIG. 7, the polygonal portions 31 and 31' are in contact and carry torque. When the impeller 3 rotates slightly, the thread 34 is cut in the direction in which the impeller nut 35 tightens the hub 28 of the impeller 3. When the cylindrical parts 30, 30' are press-fitted, the torque of the impeller 3 is supported by the frictional force caused by the elastic strain of the cylindrical parts 30, 30' depending on the tightening margin.

The force due to the resultant force of the volute part pressure applied to the impeller 3 gives a bending moment to the pump main shaft 2, but this is mainly caused by the cylindrical parts 30, 30', and by adding force to them, the contact part of the polygonal parts 31, 31' , and between the contact surfaces of the step 27 and the end surface 27' and between the end surface of the impeller nut 35 and the hub 28.

Regarding the processing of these polygons, if the shaft neck 29 of the attachment part of the pump main shaft 2 is not mass produced, the polygonal part 31 is machined by indexing it with a milling machine, and in the case of mass production, it is machined with a dedicated milling machine equipped with an indexing device or with a workpiece. A cutter arbor parallel to the pump main shaft 2 is cut by a polygon cutting machine (so-called polygon cutting machine) that cuts the cutter arbor parallel to the pump main shaft 2 while changing the distance between the centers of the pump main shaft and the cutter arbor as the pump main shaft rotates. The cylindrical portion 30 is formed by grinding or precision turning. The hub hole of the hub 28 is pulled out with a broach. Since the cylindrical portion 30', which requires the most precision, is a part of a circle, even if the broach has a second cut, it is conically ground, making it easy to ensure the precision of the broach.

As described above, in this invention, the shape of the hub hole of the impeller and the end of the main shaft of the pump is changed to the shape of the cylindrical part.
The center of the impeller 3 can be aligned with the pump main shaft 2 by centering the impeller 3 at 0.31', and the perpendicularity of the impeller installation can be easily achieved in the same way as when fitting a cylindrical shaft. As a result, there is no shaft end loss or stress concentration due to the keyway, so the shaft end can be made smaller, and since there is no key loss on the hub of the impeller, there is no chance of the hub cracking, and the hub diameter can be reduced. Because there is no key installation required for assembly,
It is simple, and there is no need to remove the key when pulling the pump main shaft through the mechanical seal.

This invention is not limited to the embodiments. Although the polygonal portions are shown as regular hexagons, other polygons may be used, and the polygonal portions may be equal diameter strain circles.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a pump including an embodiment of this invention, Fig. 2 is a partially enlarged detailed view of Fig. 1, Fig. 3 is a partial view showing a part of Fig. 2, and Fig. 4 is a partial view of Fig. 1. 3, FIG. 5 is a partial view showing another part of FIG. 2, FIG. 6 is a BB sectional view of FIG. 5, and FIGS. 7 and 8 are pump shaft ends. FIG. 3 is an axis-perpendicular cross-sectional view showing the assembly of the impeller. 1...Pump casing, 2...Pump main shaft,
3... Impeller, 4... Strainer, 5... Discharge port, 6... Electric motor frame, 7... Mechanical seal, 8... Stator, 9... Rotor, 11...
Motor cover, 12, 13...Bearing, 14...Connector, 15...Underwater cable, 16...Shaft neck, 17...Sliding ring, 18...Fixed liner ring, 19...Sealing ring, 21... Machine screw, 22...
Holding plate, 23, 24...Sliding ring, 25...Moving ring, 26...Spring, 27...Step, 28...Hub,
29... Impeller mounting part shaft neck, 30, 31'... Cylindrical part, 31, 31'... Polygonal part, 32... Relief groove, 33... Introductory part, 34... Male thread, 35...
Nut, m...Distance between opposite sides, d1, d2...Diameter, d3...Taper small end diameter, D1...Diameter, M...
...distance between opposite sides.

Claims (1)

[Scope of utility model registration request] The shaft neck of the impeller attachment part of the pump shaft and the hub hole of the impeller are each formed into polygonal parts with a polygonal cross section, and the corners of the polygonal parts are made into circular cylindrical parts centered on the pump shaft axis, The cylindrical part of the shaft neck of the pump shaft and the cylindrical part of the hub hole of the impeller are the fitting parts for centering the pump shaft and the impeller, and the shaft neck of the pump shaft and the hub hole of the impeller are polygonal. The mounting shape of the pump shaft and impeller is such that the hub hole of the impeller is fitted into the shaft neck of the pump shaft so that each side of the part is fitted with play.