JP7029991B2 - Cascade pump - Google Patents

Description

The present invention relates to a cascade pump.

Conventionally, a cascade pump equipped with an impeller having a plurality of blade grooves formed on the outer peripheral edge portion has been used. The housing accommodating the impeller is formed with a step-up flow path along the circumferential direction of the impeller (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 1-53089

Cascade pumps can increase fluid pressure even at low flow rates. In a cascade pump, the fluid becomes high pressure, so it is required to surely prevent the fluid from leaking from the sealed portion.

One aspect of the present invention is to provide a cascade pump capable of preventing fluid leakage.

One aspect of the present invention is an impeller having a plurality of blade grooves on the outer peripheral edge portion and pumping the fluid by rotation, a suction flow path for guiding the fluid to the impeller, and the fluid along the circumferential direction of the impeller. A pump housing having a boosting flow path for boosting, a discharge flow path for discharging the fluid boosted by the boosting flow path, and a circulation flow path for guiding the fluid in the discharge flow path, and a rotating shaft for rotating the impeller. A motor having a rotor connected to the rotary shaft and a stator that rotationally drives the rotor, a tubular can that separates the rotor and the stator, and the motor and the can are accommodated. A can flow path that guides the fluid from the circulation flow path between the can and the rotor, and a fluid that has passed through the can flow path is the rotor in the motor housing. A return flow path is formed to guide the pump housing into the pump housing through between the rotor and the rotary shaft, and the intermediate chamber into which the fluid from the return flow path is introduced and the fluid in the intermediate chamber are introduced into the pump housing. Provided is a cascade pump in which a return flow path leading to a suction flow path is formed.

The rotary shaft has a solid structure, and it is preferable that the pump housing is provided with a shaft support portion that rotatably supports the central portion of one end of the rotary shaft.

It is preferable that the intermediate chamber is formed on the radial inward side of the impeller from the suction flow path when viewed in parallel with the rotation axis.

The can is preferably formed integrally with the motor housing.

One aspect of the present invention comprises a can that separates the rotor and stator of the motor and circulates fluid within the can. Therefore, it is not necessary to adopt a mechanical seal structure, and it is possible to prevent fluid leakage. According to the above aspect, since the fluid can be circulated in the pump housing through the can flow path and the return flow path, it is not necessary to form a return flow path on the rotating shaft. Therefore, as compared with the case where the rotating shaft has a through flow path, the processing cost of the rotating shaft becomes unnecessary, and the manufacturing cost can be reduced.

It is a block diagram which shows the cross section along the central axis of the cascade pump of 1st Embodiment. It is a figure which shows the cross section along the line AA of FIG. It is a perspective view which shows the internal structure of the cascade pump of FIG. It is a figure which shows the cross section along the CC line of FIG. It is a figure which shows the bearing at the position shown by the line BB of FIG. It is a figure which shows the support structure of the end of the rotary shaft of the cascade pump of FIG. 1, and is the enlarged view of the part D of FIG. It is a figure which shows another example of the support structure of the end of the rotary shaft of a cascade pump. It is a block diagram which shows the cross section along the central axis of the cascade pump of 2nd Embodiment. FIG. 8 is a view of the closing portion of the can of the cascade pump of FIG. 8 as viewed from the front side.

[First Embodiment]
FIG. 1 is a configuration diagram showing a cross section of the cascade pump 10 of the first embodiment along the central axes C1 and C2. FIG. 2 is a diagram showing a cross section taken along the line AA of FIG. FIG. 3 is a perspective view showing the internal structure of the cascade pump 10. FIG. 4 is a diagram showing a cross section taken along the line CC of FIG. FIG. 5 is a diagram showing the bearing 6 at the position shown by the line BB in FIG. 1. FIG. 6 is a diagram showing a support structure at the end of the rotating shaft of the cascade pump 10, and is an enlarged view of a portion D in FIG. 1.

As shown in FIG. 1, the cascade pump 10 includes an impeller 1, a pump housing 2, a motor 3, a can 4, a motor housing 5, and a bearing 6.
Hereinafter, it is assumed that the impeller 1 is located in front of the motor 3, and the positional relationship of each member may be described. The central axis C1 is the central axis of the impeller 1. The central axis C2 is the central axis of the motor 3. The first surface 11a is the front surface of the impeller main body 11, and the second surface 11b is the rear surface of the impeller main body 11.

As shown in FIGS. 2 and 3, the impeller 1 has a disk-shaped impeller main body 11 and a protruding cylinder portion 12. The impeller main body 11 includes a central plate portion 13, a main plate portion 14, and a blade portion 15 from the central portion toward the outside in the radial direction.

The central plate portion 13 is formed in a disk shape. An insertion hole 16 (see FIG. 1) through which the rotating shaft 31 is inserted is formed in the center of the central plate portion 13. The insertion hole 16 is formed so as to penetrate the central plate portion 13 in the thickness direction. In the central plate portion 13, one or a plurality of communication holes 17 are formed at positions outside the radial direction of the insertion holes 16. The communication hole 17 is formed so as to penetrate the central plate portion 13 in the thickness direction. In FIGS. 2 and 3, four communication holes 17 are formed in the central plate portion 13 at equal intervals in the circumferential direction of the impeller 1. The communication hole 17 communicates the first space 27 and the second space 28 of the intermediate chamber 25.

The main plate portion 14 is on the outer side in the radial direction from the central plate portion 13 and is formed thicker than the central plate portion 13. The main plate portion 14 is an annular portion having a constant width in the circumferential direction of the impeller 1. As shown in FIG. 1, the front surface of the main plate portion 14 is close to the inner surface of the pump housing 2 and partitions the first space 27. The rear surface of the main plate portion 14 is close to the inner surface of the wall portion of the pump housing 2 on the motor housing 5 side, and partitions the second space 28.

As shown in FIGS. 2 and 3, the blade portion 15 is formed on the outer peripheral edge portion of the impeller main body 11. The blade portion 15 has a plurality of blade grooves 18 arranged in the circumferential direction. The blade grooves 18 are formed on both sides of the blade portion 15, respectively. The blade groove 18 is formed along the radial direction of the impeller 1. The blade groove 18 gradually increases in depth toward the outside in the radial direction.

As shown in FIG. 3, the protruding cylinder portion 12 is formed in a cylindrical shape. It protrudes from the central plate portion 13 toward the first surface 11a of the impeller main body 11 along the central axis C1. A rotating shaft 31 is inserted through the protruding cylinder portion 12.
The impeller 1 rotates in the counterclockwise direction in FIG.

As shown in FIGS. 2 and 3, the pump housing 2 houses the impeller 1. The pump housing 2 has a suction flow path 21, a step-up flow path 22, a discharge flow path 23, and a circulation flow path 24.
The suction flow path 21 can guide the fluid to the impeller 1.
The step-up flow path 22 is a flow path formed in a C shape along the circumferential direction of the impeller 1. One end of the step-up flow path 22 is connected to the suction flow path 21. The other end of the boost flow path 22 is connected to the discharge flow path 23. The fluid in the step-up flow path 22 flows in the counterclockwise direction in FIG. 2 while being boosted by the blade portion 15 of the impeller 1.
The discharge flow path 23 discharges the fluid boosted by the boost flow path 22 to the outside.

As shown in FIG. 1, the circulation flow path 24 is formed so as to penetrate the wall portion of the pump housing 2 on the motor housing 5 side. The circulation flow path 24 communicates the discharge flow path 23 with the space inside the motor housing 5. The circulation flow path 24 can introduce a part of the fluid in the discharge flow path 23 into the motor housing 5.

The motor 3 includes a rotating shaft 31, a rotor 32, and a stator 33.
The rotation shaft 31 is fixed to the impeller 1 and rotates the impeller 1. The rotor 32 is fixed to the rotating shaft 31. The rotating shaft 31 has a solid structure. As shown in FIG. 6, a receiving recess 31b into which the tip portion 30a of the shaft support portion 30 is inserted is formed in the center of the end surface of the front end 31a of the rotating shaft 31. The receiving recess 31b is formed, for example, in a shape (mortar shape) that increases in depth toward the central axis C1.

As shown in FIG. 1, the rotor 32 is arranged inside the stator 33. The rotor 32 may be coated with a resin. This makes it possible to prevent corrosion due to contact with the fluid.
The stator 33 rotationally drives the rotor 32 by an electromagnetic action.

The can 4 has a cylindrical body portion 41 having a central axis C2 as a central axis, and a disk-shaped closing portion 42 that closes the rear end opening of the body portion 41. The can 4 is made of a non-magnetic material. Since the can 4 accommodates the rotor 32, it separates the rotor 32 and the stator 33. The can 4 is preferably formed integrally with the motor housing 5. As a result, the number of parts can be reduced and the productivity can be increased.
The motor housing 5 houses the motor 3 and the can 4.

As shown in FIG. 1, a can flow path 51 and a return flow path 52 are formed in the motor housing 5.
The can flow path 51 is a flow path secured between the can 4 and the rotor 32. The can flow path 51 guides the fluid flowing into the motor housing 5 through the circulation flow path 24 to the rear space 53 of the rotor 32 via between the body portion 41 and the rotor 32.

The return flow path 52 has a rotor flow path 52A and a bearing flow path 52B.
The rotor flow path 52A is formed between the inner peripheral surface of the rotor 32 and the outer peripheral surface of the rotating shaft 31. As shown in FIG. 4, the rotor flow path 52A is formed by one or a plurality of grooves 32a formed on the inner peripheral surface of the rotor 32. In FIG. 4, the four grooves 32a are formed around the central axis C2 at intervals. As shown in FIG. 1, the groove 32a is formed along the central axis C2. The rotor flow path 52A guides the fluid in the rear space 53 forward.

The bearing 6 includes a cylindrical main portion 61 and a flange portion 62 formed at the rear end of the main portion 61. As shown in FIG. 5, the rear surface 62a of the flange portion 62 is formed with an annular circumferential groove 63 along the inner peripheral edge of the rear surface 62a and a vertical groove 64 along the radial direction of the flange portion 62. The circumferential groove 63 allows the rotor flow path 52A and the bearing flow path 52B to communicate with each other.

The bearing flow path 52B is formed between the inner peripheral surface of the bearing 6 and the outer peripheral surface of the rotating shaft 31. As shown in FIG. 5, the bearing flow path 52B is formed by one or a plurality of grooves 6a formed on the inner peripheral surface of the main portion 61 (see FIG. 1) of the bearing 6. In FIG. 5, the four grooves 6a are formed at intervals around the central axis C2. As shown in FIG. 1, the groove 6a is formed along the central axis C2. The bearing flow path 52B guides the fluid from the rotor flow path 52A into the pump housing 2 (intermediate chamber 25).

An intermediate chamber 25 and a return flow path 26 are formed in the pump housing 2.
The intermediate chamber 25 has a first space 27 and a second space 28. The first space 27 is in front of the impeller main body 11 and is a space on the inner side in the radial direction from the main plate portion 14. The second space 28 is located behind the impeller main body 11 and is a space on the inner side in the radial direction from the main plate portion 14. The first space 27 and the second space 28 are communicated with each other by a communication hole 17. A fluid is introduced into the intermediate chamber 25 from the return flow path 52 (specifically, the bearing flow path 52B).

As shown in FIG. 2, the return flow path 26 is a flow path formed by a groove 29 (see FIG. 1) on the inner surface of the pump housing 2. The return flow path 26 communicates the intermediate chamber 25 with the suction flow path 21. The return flow path 26 can introduce the fluid in the intermediate chamber 25 into the suction flow path 21.

As shown in FIG. 6, the pump housing 2 is formed with a shaft support portion 30 that rotatably supports the central portion of the front end 31a (one end) of the rotary shaft 31. The shaft support portion 30 projects rearward from the inner surface of the pump housing 2. The tip portion 30a of the shaft support portion 30 is formed in a conical shape that narrows toward the tip. The inclination angle of the outer surface of the tip portion 30a with respect to the central axis C1 is smaller than the inclination angle of the inner surface of the receiving recess 31b. The tip portion 30a is inserted into the receiving recess 31b of the rotating shaft 31. The tip of the tip portion 30a abuts on the central portion of the inner surface of the receiving recess 31b and supports the front end portion (the portion including the front end 31a) of the rotating shaft 31.

Next, the operation of the cascade pump 10 will be described.
As shown in FIGS. 2 and 3, when the impeller 1 rotates, a fluid (for example, a liquid such as water) is introduced into the pump housing 2 from the suction flow path 21. The fluid flows into the step-up flow path 22 and is boosted by the blade portion 15 of the impeller 1. The boosted fluid is discharged to the outside through the discharge flow path 23.

As shown in FIG. 1, a part of the fluid in the discharge flow path 23 is introduced into the motor housing 5 through the circulation flow path 24. The fluid is introduced into the rear space 53 through the can flow path 51. The fluid is guided forward from the rear space 53 through the return flow path 52 and flows into the intermediate chamber 25 of the pump housing 2. The fluid in the intermediate chamber 25 is introduced into the suction flow path 21 through the return flow path 26. As described above, a part of the fluid in the suction flow path 21 is transferred from the suction flow path 21, the step-up flow path 22, the discharge flow path 23, the circulation flow path 24, the can flow path 51, the return flow path 52, and the intermediate chamber 25. , And circulates in the suction flow path 21 via the return flow path 26. In the process of circulation, the fluid cools the motor 3. The fluid flowing through the return flow path 26 can also function as a lubricating liquid between the pump housing 2 and the impeller 1.

The cascade pump 10 includes a can 4 that separates the rotor 32 of the motor 3 and the stator 33, and circulates the fluid in the can 4. Therefore, it is not necessary to adopt a mechanical seal structure, and it is possible to prevent fluid leakage.
Since the cascade pump 10 can circulate the fluid in the pump housing 2 through the can flow path 51 and the return flow path 52, it is not necessary to form a return flow path on the rotating shaft 31. Therefore, as compared with the case where the rotating shaft has a through flow path, the processing cost of the rotating shaft becomes unnecessary, and the manufacturing cost can be reduced.

Since the cascade pump 10 does not need to form a through flow path in the rotating shaft 31, the front end 31a of the rotating shaft 31 can be supported by the shaft supporting portion 30. Therefore, the impeller 1 can be operated stably.

Since the intermediate chamber 25 into which the fluid returned by the return flow path 52 is introduced is formed on the radial inward side of the impeller 1 as compared with the suction flow path 21, the space in the pump housing 2 is effectively used. can do. Therefore, it is advantageous in reducing the size of the cascade pump 10.

[Modified example of the first embodiment]
FIG. 7 is a diagram showing another example of the support structure at the end of the rotary shaft of the cascade pump.
As shown in FIG. 7, a receiving recess 131b into which the tip end portion of the shaft support portion 130 is inserted is formed on the end surface of the front end 131a of the rotating shaft 131. The receiving recess 131b is, for example, a recess having a hemispherical inner surface. The shaft support portion 130 projects rearward from the inner surface of the pump housing 2. The tip portion 130a of the shaft support portion 130 is formed in a curved convex shape (for example, hemispherical shape). The radius of curvature of the outer surface of the tip portion 130a is smaller than the radius of curvature of the inner surface of the receiving recess 131b. The tip of the tip portion 130a abuts on the central portion of the inner surface of the receiving recess 131b and supports the front end portion (the portion including the front end 131a) of the rotating shaft 131.
According to this structure, the tip portion 130a of the shaft support portion 130 can stably support the front end 131a of the rotating shaft 131.

[Second Embodiment]
FIG. 8 is a configuration diagram showing a cross section of the cascade pump 110 of the second embodiment along the central axis C1. FIG. 9 is a view of the closing portion 142 of the can 104 of the cascade pump 110 as viewed from the front side. Hereinafter, the same reference numerals are given to the structures common to the cascade pump 10 of the first embodiment, and the description thereof will be omitted.

As shown in FIG. 8, the cascade pump 110 includes an impeller 1, a pump housing 2, a motor 3, a can 104, a motor housing 105, a first bearing 106A, and a second bearing 106B.
The first bearing 106A has the same configuration as the bearing 6 used in the cascade pump 10 of the first embodiment shown in FIG.

The second bearing 106B is provided at a position rearward from the first bearing 106A. The second bearing 106B includes a cylindrical main portion 161 and a flange portion 162 formed at the front end of the main portion 161. As shown in FIGS. 8 and 9, a groove 164 is formed on the inner surface of the closing portion 142 of the can 104 facing the main portion 161 and the flange portion 162.

A can flow path 151 and a return flow path 152 are formed in the motor housing 105.
The can flow path 151 allows the fluid flowing into the motor housing 105 through the circulation flow path 24 to pass between the body portion 41 and the rotor 32 and to pass through the outer surface side (groove 164) of the second bearing 106B to the second bearing. Lead to the rear side of 106B.

The return flow path 152 has a bearing flow path 152C, a rotor flow path 52A, and a bearing flow path 152B.
The bearing flow path 152C is formed between the inner peripheral surface of the second bearing 106B and the outer peripheral surface of the rotating shaft 31. The bearing flow path 152C is formed by one or a plurality of grooves formed on the inner peripheral surface of the main portion 161 of the second bearing 106B.
The bearing flow path 152B is formed between the inner peripheral surface of the first bearing 106A and the outer peripheral surface of the rotating shaft 31. The bearing flow path 152B is formed by one or a plurality of grooves formed on the inner peripheral surface of the main portion 61 of the first bearing 106A.

Next, the operation of the cascade pump 110 will be described.
As shown in FIG. 8, when the impeller 1 rotates, the fluid flows from the suction flow path 21 into the step-up flow path 22, is boosted by the blade portion 15 of the impeller 1, and is discharged from the discharge flow path 23.

A part of the fluid in the discharge flow path 23 is introduced into the motor housing 5 through the circulation flow path 24. The fluid is introduced to the outer surface side (groove 164) of the second bearing 106B through the can flow path 151. The fluid is guided forward through the bearing flow path 152C, the rotor flow path 52A, and the bearing flow path 152B of the return flow path 152, and flows into the intermediate chamber 25 of the pump housing 2. The fluid in the intermediate chamber 25 is introduced into the suction flow path 21 through the return flow path 26.

Since the cascade pump 110 has two bearings 106A and 106B, the rotating shaft 31 can be supported at a plurality of points and the operation of the impeller 1 can be stabilized.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

1 ... Impeller, 2 ... Pump housing, 3 ... Motor, 4,104 ... Can, 5,105 ... Motor housing, 10,110 ... Cascade pump, 15 ... Blade, 18 ... Blade groove, 21 ... Suction flow path, 22 ... Boost flow path, 23 ... Discharge flow path, 24 ... Circulation flow path, 25 ... Intermediate chamber, 26 ... Return flow path, 30, 130 ... Shaft support, 31 ... Rotating shaft, 31a ... Front end (one end), 32 ... Rotor, 33 ... stator, 51, 151 ... can flow path, 52, 152 ... return flow path.

Claims (4)

An impeller that has multiple blade grooves on the outer peripheral edge and pumps fluid by rotation,
A suction flow path that guides the fluid to the impeller, a boost flow path that boosts the fluid along the circumferential direction of the impeller, a discharge flow path that discharges the fluid boosted by the boost flow path, and a discharge flow path. A pump housing having a circulation flow path, which guides the fluid in, and
A motor having a rotating shaft for rotating the impeller, a rotor connected to the rotating shaft, and a stator for rotating and driving the rotor.
A cylindrical can that separates the rotor and the stator,
A motor housing that houses the motor and the can,
A bearing that supports the rotating shaft between the rotor and the impeller,
Equipped with
In the motor housing, a can flow path that guides the fluid from the circulation flow path between the can and the rotor, and the fluid that has passed through the can flow path between the rotor and the rotation shaft. A return flow path is formed through which leads into the pump housing.
An intermediate chamber into which the fluid from the return flow path is introduced and a return flow path that guides the fluid in the intermediate chamber to the suction flow path are formed in the pump housing.
The return flow path is
A rotor flow path formed by one or more grooves formed on the inner peripheral surface of the rotor, and a rotor flow path.
It has a bearing flow path formed by one or more grooves formed on the inner peripheral surface of the bearing, and has.
A circumferential groove is formed in the bearing to allow the rotor flow path and the bearing flow path to communicate with each other.
The circumferential groove is formed in an annular shape on the end face of the bearing on the rotor side along the inner peripheral edge of the end face.
Cascade pump. The axis of rotation has a solid structure and has a solid structure.
The cascade pump according to claim 1, wherein the pump housing is provided with a shaft support portion that rotatably supports a central portion of one end of the rotary shaft. The cascade pump according to claim 1 or 2, wherein the intermediate chamber is formed on the radial inward side of the impeller from the suction flow path when viewed in parallel with the rotation axis. The cascade pump according to any one of claims 1 to 3, wherein the can is integrally formed with the motor housing.

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