JP3929223B2 - Canned motor pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a canned motor pump, and more particularly to a canned motor pump manufactured using an impeller of an existing centrifugal pump.
[0002]
[Prior art]
FIG. 8 is a diagram showing a general structure of a centrifugal pump. As shown in FIG. 8, an impeller 2 is disposed inside the pump casing 1 of the pump unit, and a casing cover 3 is fixed to an opening on the high pressure side of the pump casing 1. One end of the rotor 5 is inserted into the casing cover 3, and the impeller 2 is fixed to one end of the rotor 5 via a bolt. Near the center of the rotor 5, bearings 9 a and 9 b that support loads including axial and radial weights acting on the rotor 5 are arranged in the bearing casing 15. The rotor 5 is rotatably supported via bearings 9a and 9b. In addition, a mechanical seal 16 is mounted on the inner periphery of the casing cover 3 for limiting the amount of liquid handled by the pump from the high pressure side of the pump casing 1 to the atmosphere side.
[0003]
In such a centrifugal pump, the discharge amount can be applied from a small flow rate to a large flow rate with a single type (for example, a single suction single-stage horizontal process pump), and the total lift also ranges from a low lift to a high lift. As applicable, even with the same model, 10 to 50 types of pumps having the same structure but different dimensions are commercialized as a series so that the optimum pump can be selected for various specifications.
[0004]
Basically, all types of pump parts can be manufactured with different dimensions. However, in terms of manufacturing, the number of parts (number of lots) generated per part of a part is reduced, and it is difficult to reduce the cost of the parts, and the inventory management of the parts becomes complicated. For users, it seems that maintenance will not be hindered if only one pump is used. However, if many pumps of the same type are used at the plant, etc. It is necessary to prepare parts in advance, which is considerably complicated in terms of management.
In order to minimize manufacturing costs, to facilitate inventory management, and to facilitate maintenance, in general, parts are shared as much as possible. Pump manufacturers that have commercialized various types of pumps have a tendency to share parts even between different types.
[0005]
In the field of pumps, “energy saving” and “reuse (reuse)” are attracting attention from the viewpoint of “environmental protection”, and there is a current situation that cannot be avoided. In addition, the number of maintenance personnel has decreased due to labor savings, and the number of personnel with skills to incorporate and replace mechanical seals and gland packings and make adjustments during operation is also decreasing.
One of the solutions for environmental protection and energy saving is to remodel existing pumps with mechanical seals or pumps with gland packing into canned motor pumps that prevent the handling liquid from leaking outside. In addition, various types of centrifugal pumps that have already been commercialized may be modified to a canned motor pump from the beginning of installation to cope with labor saving. The canned motor pump is called a “sealless pump” under the general name, but even if it does not have a mechanical seal or gland packing, it is a pump that can serve as a seal that does not leak the handling liquid to the outside. is there.
[0006]
In this way, when remodeling an existing pump to a canned motor pump, the pump capacity (discharge amount and total head) cannot be changed, so it is necessary to reuse the existing pump casing and impeller. It does n’t take long, it ’s the best. The main parts that can be reused are a base (not shown) on which a pump and a driving machine are installed in addition to the pump casing and the impeller. The pump casing and the impeller are relatively expensive among the pump components, and the remodeling cost can be reduced by reusing. And it is consistent with the gist from the viewpoint of environmental protection. Further, by reusing the pump casing, the suction pipe (not shown) and the discharge pipe (not shown) can be reused as they are. In addition, by reusing the base, it is not necessary to reconstruct the foundation concrete or the like.
And after remodeling to a canned motor pump, the maintenance which only replaces a bearing for every 1 to 3 years is enough.
[0007]
[Problems to be solved by the invention]
However, in the existing centrifugal pump, the liner diameter for limiting the amount of leakage between the impeller 2 and the casing cover 3 is the same on the main plate 2a side and the side plate 2b side, and the main plate 2a side is larger. The side plate 2b has a larger size, such as a larger one. In some cases, the impeller has no side plate 2b.
However, if the liner diameter for limiting the amount of leakage in the gap between the impeller and the casing cover exists at different positions on the pump suction side and the anti-suction side, this causes the axial thrust to be on the pump suction side or the anti-suction side. Applied to the side, causing bearing wear.
[0008]
In general, in a canned motor pump, it is computationally possible to determine the dimensions of each part so as to balance the axial thrust, but it is practically difficult. Actually, the direction of the axial thrust may vary due to pressure pulsations, changes in the gaps constituting the flow path, or variations in the viscosity of the liquid. That is, the axial thrust direction fluctuates repeatedly at a considerably high frequency (product of the number of blades of the impeller 2 and the operating frequency of the pump) on the suction side and the counter suction side.
And when it fluctuates constantly, the rotor 5 vibrates in the axial direction, increasing the axial vibration of the entire canned motor pump. In order to prevent the rotor 5 from vibrating in the axial direction during pump operation, in general, a certain amount of axial thrust remains in one direction so that an excessive thrust load is not applied to the bearing ( Hereinafter, each dimension is determined. If it is designed so that the residual axial thrust of the canned motor pump used for remodeling is on the suction side, the axial thrust further increases, the load acting on the bearing increases, and the life of the bearing increases. Will be reduced. Alternatively, in the case where the residual axial thrust of the canned motor used for remodeling is designed to be on the anti-suction side, vibration in the axial direction may occur.
[0009]
The present invention has been made in view of the above circumstances, and when an existing centrifugal pump is remodeled into a canned motor pump, the axial load applied to the bearing is reduced by reducing the axial thrust acting on the impeller. And it aims at providing the canned motor pump which improved the bearing life.
[0010]
[Means for Solving the Problems]
Canned motor pump of the present invention, there is provided a canned motor pump fabricated using the impeller of the existing centrifugal pump, leakage pump is formed between the impeller fixed member and the casing cover of the centrifugal pump When the liner diameter on the main plate side is larger than the liner diameter on the side plate side of the impeller of the centrifugal pump having the main plate so that the radial position of the gap limiting the amount is substantially equal on the suction side and the anti-suction side If the impeller pressure adjusting ring is attached to the inner peripheral side of the impeller main plate side liner, or if the liner diameter on the main plate side is smaller than the liner diameter on the side plate side, the impeller main plate side of the outer peripheral side of the liner characterized in that fitted with pressure adjustment ring for the impeller.
[0011]
When the liner diameter, which is a gap for limiting the amount of leakage between the impeller and the casing cover, is approximately equal on the suction side and the anti-suction side, the axial thrust is approximately equal on both sides. Therefore, even if the operating point of the pump is changed, the vibration in the axial direction is small and stable operation can be obtained.
[0012]
Further, the adjusting unit, when the liner diameter of the main plate side of the impeller of the centrifugal pump is large with the main plate, and wherein the attaching the pressure adjustment ring for the impeller on the inner peripheral side of the impeller liner .
Thereby, the substantial liner diameter of the suction side and the anti-suction side can be made substantially equal, and the axial thrust acting on the anti-suction side of the impeller can be reduced.
[0013]
The front Symbol adjusting unit, when the liner diameter of the main plate side of the impeller of the centrifugal pump is small having a main plate, and wherein the attaching the pressure adjustment ring for the impeller at the outer peripheral side of the impeller liner .
Thereby, the substantial liner diameter of the suction side and the anti-suction side can be made substantially equal, and the axial thrust acting on the suction side of the impeller can be reduced.
[0014]
The method for manufacturing a canned motor pump according to the present invention includes a pump impeller fixed to a rotor, a can-sealed rotor of a motor unit, the rotor supported by a bearing, the bearing and the motor unit In a method of manufacturing a canned motor pump in which a part of pump handling liquid is circulated in a gap between a rotor and a stator of a motor unit, an impeller of an existing centrifugal pump is used, and the blade of the centrifugal pump is used. Centrifugal pump blades having a main plate so that a gap formed between the vehicle and the casing cover for limiting the amount of pump leakage is substantially equal in radial direction between the suction side and the anti-suction side of the pump. When the liner diameter on the main plate side is larger than the liner diameter on the side plate side of the car, a pressure adjusting ring for the impeller is attached to the inner peripheral side of the main plate side liner of the impeller, or the side plate side liner is attached. If small liner diameter of the main plate side than the diameter is adjusted to the outer peripheral side of the impeller main plate side of the liner fitted with a pressure adjustment ring for the impeller, characterized by fabricating the pump.
[0015]
Thus, when retrofitting an existing centrifugal pump to the canned motor pump, Ru can modify the canned motor pump having a reduced axial thrust acting on the impeller.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a canned motor pump according to a first embodiment of the present invention. This example reuses the impeller 2 and the pump casing 1 whose liner diameter, which is a gap for limiting the amount of leakage between the impeller 2 and the casing cover 3, is larger on the main plate 2a side than on the side plate 2b side, It shows an example of the structure when modified to a canned motor pump.
[0017]
As shown in FIG. 1, an impeller 2 is disposed inside a pump casing 1 of the pump unit, and a casing cover 3 is fixed to an opening on the high pressure side of the pump casing 1. In addition, the casing cover 3 is formed with a flow hole 4 that guides a part of the pump-treated liquid whose pressure has been increased after passing through the impeller 2 to the space A described below. One end of the rotor 5 is inserted into the casing cover 3, and a distance piece (sleeve) 6, a thrust plate 7 a, a shaft sleeve 8 a and an impeller 2 fitted to the rotor 5 are bolted to one end of the rotor 5. The thrust plate 7b and the shaft sleeve 8b are fixed to the other end of the rotor 5 via bolts.
[0018]
The rotor 5 is rotatably supported at both ends thereof via a pair of bearings 9a and 9b, and a rotor 10 of a motor unit is fixed at substantially the center thereof.
A pressure liquid chamber is provided between the bearing 9a on the impeller side, the casing cover 3, the distance piece (sleeve) 6 and the shaft sleeve 8a by providing an inwardly protruding convex portion 3a on the inner peripheral surface of the casing cover 3. And a space C between the rotor 10 and the impeller side bearing 9a, and a space C between the rotor 10 and the impeller 2 on the opposite side bearing 9b. A space D is provided between the end cover 11 and the bearing 9 b on the opposite side of the impeller 2, and a space E is further provided between the casing cover 3 and the impeller 2.
[0019]
The flow path a is fixed between the impeller side bearing 9a and the shaft sleeve 8a, and the flow path b is fixed between the end face of the impeller side bearing 9a and the thrust plate 7a, and the can 12a of the rotor 10. The flow path c is between the can 12b of the child 13 and the flow path d is between the end face of the bearing 9b opposite to the impeller 2 and the thrust plate 7b. The bearing 9b is opposite to the impeller 2 and the shaft sleeve. The flow path e is each comprised between 8b. A flow path f is formed between the inner peripheral surface of the convex portion 3 a of the casing cover 3 and the distance piece 6. A through hole 14 penetrating in the axial direction is formed inside the rotor 5, and the through hole 14 is open on both sides including bolts at both ends. The through hole 14 allows the space D between the end cover 11 and the impeller 2 and the bearing 9b on the opposite side to communicate with the pump suction side.
[0020]
In the canned motor pump having the above-described configuration, the pump-treated liquid whose pressure has been increased after passing through the impeller is guided from the flow hole 4 provided in the casing cover 3 into the space A that constitutes the pressure liquid chamber, and from there in two directions. Flowing. The first flow passes through the flow path f formed between the inner peripheral surface of the convex portion 3 a of the casing cover 3 and the distance piece 6, then enters the space E, and passes through the balance hole 2 c of the impeller 2. The flow returns to the suction side of the pump. The second flow passes from the space A through the flow channel a, the flow channel b, the space B, the flow channel c, the space C, the flow channel d, the flow channel e, the space D, and the through hole 14 in order. The flow returns to the suction side.
[0021]
Since both the first flow and the second flow finally lead to the suction side of the pump, the pump-treated liquid whose pressure has been increased after passing through the impeller is sucked from the space A from the suction of the pump which is a lower pressure part. And the second flow cools the motor part and cools and lubricates the bearings 9a and 9b. Further, the pressure in the space E can be made substantially the same value as the suction pressure because the pressure loss can be hardly caused by sufficiently increasing the area of the balance hole 2c of the impeller 2.
The dimensions of each part for constituting these flow paths are determined so as to obtain a circulating amount of pump handling liquid necessary for reliably cooling the motor part and cooling and lubricating the bearings 9a and 9b. Yes.
[0022]
Here, if the magnitude relationship of each pressure of the space A, the space B, the space C, the space D, the space E, and the suction pressure is Pa, Pb, Pc, Pd, Pe, and Ps, respectively,
Pa> Pe≈Ps
And,
Pa>Pb>Pc>Pd> Ps
It becomes.
Therefore, the axial thrust that acts on the rotor 5 including the impeller 2 is an axial thrust that acts on the rotor 10, an axial thrust that acts on the outer diameter cross section of the shaft sleeve in the space D, an axial thrust that acts on the impeller, and the like. Summed up.
[0023]
In FIG. 2, the main plate 2a and the side plate 2b of the impeller 2 have a liner diameter for limiting the amount of leakage between the impeller 2 and the casing cover 3 on the main plate 2a side (Ra) is larger than the side plate 2b side (Rb). The pressure distribution in the axial direction acting on the surface is shown. In the same figure, line segments A, U, Oka, Kiku, and Kosa each indicate pressure in the axial direction, the length of the line segment indicates the magnitude of pressure, and the arrow indicates the direction of pressure.
As shown in the figure, the pressure acting on the both sides of the main plate 2a and the side plate 2b gradually decreases from the outer diameter of the impeller 2 toward the liner portion. The pressure eye on the main plate 2a side and the pressure on the side plate 2b side at the outer diameter of the impeller 2 may be regarded as equal. Similarly, the pressure well on the main plate 2a side and the pressure rise on the side plate 2b side may be regarded as equal.
Therefore, when the liner diameter is larger on the side of the main plate 2a (Ra> Rb), the liner diameter is smaller than the pressure plate and the pressure rib compared to the case where the main plate 2a side is equal to the side plate 2b side. As much as the axial thrust increases on the anti-suction side.
[0024]
FIG. 3 shows the main plate 2a and side plate 2b of the impeller 2 in which the liner diameter for limiting the amount of leakage between the impeller 2 and the casing cover 3 is smaller on the main plate 2a side (Ra) than on the side plate 2b side (Rb). The axial pressure distribution acting on the surface is shown. In FIG. 3, line segments Ai, Ue, Oka, Kiku, and Sis each indicate pressure in the axial direction, the length of the line segment indicates the magnitude of pressure, and the arrow indicates the direction of pressure.
As shown in FIG. 3, on both surfaces of the main plate 2a and the side plate 2b, the acting pressure gradually decreases from the outer diameter of the impeller 2 toward the liner portion. The pressure eye on the main plate 2a side and the pressure on the side plate 2b side at the outer diameter of the impeller 2 may be regarded as equal. Similarly, the pressure cis on the main plate 2a side and the pressure crack on the side plate 2b side may be regarded as equal. Therefore, when the liner diameter is smaller than the side plate 2b side on the main plate 2a side (Ra <Rb), compared with the case where the liner diameter is equal on the main plate 2a side and the side plate 2b side, Only the axial thrust on the suction side becomes larger.
[0025]
If the residual axial thrust of the optimal canned motor used for remodeling is designed to be on the suction side, the rotor 5 is not stabilized in order to reduce the expected residual axial thrust. Vibration exceeding the normal value may occur in the axial direction. Alternatively, in the case where the residual axial thrust of the canned motor is designed to be on the anti-suction side, in addition to the expected residual axial thrust, the axial thrust further increases and the load acting on the bearing 9b increases. As a result, the life of the bearing 9b is reduced.
[0026]
FIG. 4 is a view showing a cross section and a pressure distribution of the impeller according to the first embodiment of the present invention.
As shown in FIG. 4, a replaceable pressure adjusting ring 2 d is attached to the inner peripheral side of the main plate 2 a of the impeller 2. Further, a leakage amount limiting gap (liner) with the casing cover 3 can be provided on the inner periphery of the pressure adjusting ring 2d.
As a result, the axial pressure distribution acting on the surfaces of the main plate 2a and the side plate 2b is made almost equal while using the same impeller 2 as that of the existing centrifugal pump described in FIG. Axial thrust acting on the side can be reduced.
[0027]
FIG. 5 is a diagram showing a cross section of an impeller and a pressure distribution acting on a main plate and a side plate of the impeller according to the second embodiment of the present invention. In this embodiment, the liner diameter of the existing centrifugal pump is shown in the case where the diameter Ra on the main plate side is smaller than the diameter Rb on the side plate side.
As shown in FIG. 5, a replaceable pressure adjusting ring 2 d is attached to the outer peripheral side of the main plate 2 a liner portion of the impeller 2. A leakage amount limiting gap with the casing cover 3 can be provided on the outer periphery of the pressure adjusting ring 2d. Therefore, the axial thrust (shown by the arrow way) acting on the main plate side (anti-suction side) and the axial thrust (shown by the arrow mark) acting on the side plate side (suction side) are balanced with each other. Therefore, a canned motor pump can be manufactured using the existing centrifugal pump impeller without increasing the wear of the bearing.
[0028]
FIG. 6 is a sectional view showing the structure of a canned motor pump incorporating the impeller described in FIG. The basic structure of the canned motor pump itself is substantially the same as that of the embodiment shown in FIG. 1, and the same or corresponding parts are denoted by the same reference numerals, and the duplicate description thereof is omitted.
[0029]
FIG. 7 is a diagram showing a cross section of a canned motor pump according to the third embodiment of the present invention. The basic structure of the canned motor pump itself is substantially the same as that of the embodiment shown in FIG. 1, and the same or corresponding parts are denoted by the same reference numerals, and redundant description thereof is omitted. In this embodiment, the existing centrifugal pump impeller 2 having a substantially equal liner diameter on the main plate side and the side plate side is employed in advance. The pump casing 1 and the casing cover 3 are also adapted to this liner. Accordingly, the axial thrust acting on the suction side or the anti-suction side of the impeller 2 can be balanced without using the pressure adjusting ring 2d for the impeller described above. Therefore, a canned motor pump can be manufactured using an existing impeller of a centrifugal pump without increasing the axial thrust acting on the bearing even by such a method.
[0030]
Next, the manufacturing method of the canned motor pump of this invention is demonstrated. First, an impeller of a centrifugal pump corresponding to the required total head, discharge amount, etc. is prepared. The impeller of this centrifugal pump is not specially designed for a canned motor pump, but is used for an existing centrifugal pump. Then, the liner diameter on the main plate side and the side plate side will be examined. When the liner diameters of the main plate side and the side plate side are substantially equal, this can be used as it is, and the pump casing 1 and the casing cover 3 matched to the impeller can be used as they are.
[0031]
When the liner diameters on the main plate side and side plate side are different, if they are used as they are, axial thrust will occur as described above, causing problems such as shortening the bearing life. A suitable pressure adjusting ring 2d is attached. And it forms so that the position of the convex part which forms the clearance gap for the leakage prevention of the pump provided in the inner peripheral surface or outer peripheral surface of the pressure adjustment ring and the casing cover 3 may be matched with the position of the liner diameter on the side plate side. To do. By doing in this way, the liner position of the main board side and the side board side can be match | combined, and, thereby, the equilibrium state of an axial thrust can be maintained.
[0032]
Here, when the liner diameter on the main plate side is larger than the liner diameter on the side plate side, a pressure adjusting ring 2d is provided on the inner peripheral side of the liner on the main plate side, thereby making the liner diameters of the both equal. Conversely, when the liner diameter on the main plate side is smaller than the liner diameter on the side plate side, the pressure adjusting ring 2d is disposed on the outer peripheral portion of the liner on the main plate side, and the liner diameter on the outer peripheral side is the liner diameter on the side plate side. To be equal to In this way, the pump impeller is processed, and the canned motor pump is manufactured according to the normal manufacturing process of the canned motor pump by using the casing cover 3 and the pump casing 1 matched to the pump impeller as components.
[0033]
The canned motor pump manufactured in this way can be used as it is or with slight processing on the existing centrifugal pump impeller, pump casing, casing cover, etc. It can be manufactured at low cost and with short delivery time. And even though the liner diameter of existing centrifugal pumps varies, by adjusting the liner diameter by the above-mentioned process, it is possible to prevent the occurrence of unnecessary axial thrust and keep the bearing life long. Therefore, even if the operating point is changed, it is possible to stably operate without generating vibration or the like.
[0034]
The above-described embodiment is an example of the embodiment of the present invention, and it goes without saying that various modified embodiments are possible.
[0035]
【The invention's effect】
Generally, according to the present invention, when remodeling into a canned motor pump using an existing impeller of a centrifugal pump, the axial load applied to the bearing is reduced by reducing the axial thrust acting on the impeller, The bearing life can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a canned motor pump according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a cross section of an impeller when a liner diameter on a main plate side is larger than a liner diameter on a side plate side, and a pressure distribution acting on the main plate and the side plate of the impeller.
FIG. 3 is a diagram showing a cross section of an impeller when a liner diameter on a main plate side is smaller than a liner diameter on a side plate side, and a pressure distribution acting on the main plate and the side plate of the impeller.
4 is a view showing a cross section of the impeller in the embodiment shown in FIG. 1 and a pressure distribution acting on a main plate and a side plate of the impeller. FIG.
FIG. 5 is a diagram showing a cross section of an impeller and a pressure distribution acting on a main plate and a side plate of the impeller according to the second embodiment of the present invention.
6 is a cross-sectional view showing the structure of a canned motor pump using the impeller shown in FIG.
FIG. 7 is a sectional view showing a canned motor pump according to a third embodiment of the present invention.
FIG. 8 is a cross-sectional view showing the structure of a conventional centrifugal pump.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump casing 2 Impeller 2a Main plate 2b Side plate 2d Pressure adjustment ring 3 Casing cover 4 Flow hole 5 Rotor 6 Sleeve 9a, 9b Bearing 10 Motor rotor 13 Motor stator 14 Through-hole

Claims (2)

A canned motor pump fabricated using the impeller of the existing centrifugal pump,
The radial position of the gap that limits the amount of pump leakage formed between the member fixed to the impeller of the centrifugal pump and the casing cover is substantially equal on the suction side and the anti-suction side .
When the liner diameter on the main plate side is larger than the liner diameter on the side plate side of the impeller of the centrifugal pump having the main plate, a pressure adjusting ring for the impeller is attached to the inner peripheral side of the main plate side liner of the impeller. Or
A canned motor pump , wherein a pressure adjustment ring for the impeller is attached to the outer peripheral side of the liner on the impeller main plate side when the liner diameter on the main plate side is smaller than the liner diameter on the side plate side . A pump impeller is fixed to the rotor, and a rotor of the motor unit sealed with a can is provided, the rotor is supported by a bearing, and a gap between the bearing, the rotor of the motor unit, and the stator of the motor unit In the method of manufacturing a canned motor pump in which a part of the pump handling liquid is circulated in
A gap that limits the amount of pump leakage formed between the centrifugal pump impeller and the casing cover using an existing centrifugal pump impeller has a radius between the suction side and the anti-suction side of the pump. So that the direction position is almost equal ,
When the liner diameter on the main plate side is larger than the liner diameter on the side plate side of the impeller of the centrifugal pump having the main plate, a pressure adjusting ring for the impeller is attached to the inner peripheral side of the main plate side liner of the impeller, or When the liner diameter on the main plate side is smaller than the liner diameter on the side plate side, a pressure adjusting ring for the impeller is attached and adjusted on the outer peripheral side of the liner on the impeller main plate side , and the pump is manufactured. A method of manufacturing a canned motor pump.

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