JP3157493U - Centrifugal pump impeller and centrifugal sanitary pump - Google Patents

Abstract

A closed type impeller suitable for a centrifugal sanitary pump that eliminates the problem of blade vibration is provided. An impeller 40 for a centrifugal pump is a closed type impeller 40 having a cylindrical suction port (vacant space 50) in an axial center portion, and opens to the suction port 50 at an inner end portion, and an outer end. A plurality of fluid flow paths 52 that are open to the outer peripheral surface of the impeller at each portion, and each fluid flow path 52 is a straight line parallel to the tangential direction of the suction port 50 and covers the entire surface including processing of the fluid flow path 52. Finished by cutting. [Selection] Figure 1

Description

  This device relates to the structure of an impeller (impeller) for a centrifugal pump, and can be used for a centrifugal sanitary pump used in a food plant or a pharmaceutical plant.

  Conventionally, centrifugal sanitary pumps used in food plants and pharmaceutical plants have been equipped with open type impellers because the pumps themselves have better cleaning properties than closed type impellers, which have excellent pump efficiency. . As is well known, a closed type impeller has a configuration in which a plurality of blades (also referred to as blades) are arranged between a main plate and a side plate, and a fluid flow path is formed between adjacent blades. On the other hand, the open type impeller has a form in which the side plate in the closed type is eliminated.

JP 2001-123981 A

  The conventional sanitary pump using an open type impeller has the following problems. When rotating at high speed with a two-pole motor, vibration (blurring) occurs at the blade tip during operation, resulting in high noise during operation and adversely affecting the work environment around the installation. In addition, the vibration has an adverse effect on the mechanical seal of the shaft seal portion, and causes a leakage accident. Furthermore, in the case of an open type impeller, it is necessary to widen the gap between the impeller blades and the casing during operation in order to prevent the wear powder from being mixed into the pumped liquid, so that the pump efficiency is improved. descend.

  On the other hand, the conventional closed type impeller has a rough surface because it is formed by casting, and casting defects such as a cast hole are likely to occur, and is not suitable for a sanitary pump that requires cleanability.

  This invention eliminates the above-mentioned problems and provides a closed type impeller suitable for a centrifugal sanitary pump.

  The impeller for a centrifugal pump according to the present invention is a closed type impeller provided with a cylindrical suction port in an axial center portion, and opens to the suction port at an inner end portion and opens to an outer peripheral surface of the impeller at an outer end portion. It has a plurality of fluid channels, and each fluid channel is a straight line parallel to the tangential direction of the suction port. The characteristic of the centrifugal pump impeller of the present invention is that there is no blade in the conventional closed type.

  According to a second aspect of the present invention, in the centrifugal pump impeller according to the first aspect, a cross section of the fluid flow path is circular. The straight fluid flow path having a circular cross section is easy to process, and thus helps to reduce the cost.

  The invention of claim 3 is characterized in that, in the impeller for centrifugal pump of claim 1 or 2, a notch for reducing an outlet angle is provided from the outer end of the fluid flow path to the outer peripheral surface of the impeller. Is. Here, the outlet angle refers to an angle formed by the fluid flow path and the outer peripheral surface of the impeller.

  According to a fourth aspect of the present invention, in the centrifugal pump impeller according to the first, second, or third aspect, the present invention is characterized in that a cylindrical outer peripheral surface protruding on both sides in the axial direction is provided. Each cylindrical outer peripheral surface plays a role in preventing pressure from escaping from the high pressure side to the low pressure side by forming a minute clearance with the corresponding cylindrical inner peripheral surface provided on the casing side (pressure holding Sliding surface).

  The invention of claim 5 is the centrifugal pump impeller according to any one of claims 1 to 4, wherein the material is a forged material or a rolled material.

  The invention of claim 6 is characterized in that in the centrifugal pump impeller of any one of claims 1 to 5, the entire surface is finished by cutting.

  A device of a seventh aspect is a centrifugal sanitary pump using the centrifugal pump impeller of any one of the first to sixth aspects. As described above, the centrifugal pump impeller of the present invention is particularly suitable for sanitary pumps because of its excellent cleaning properties.

  Since the centrifugal pump impeller of the present invention is a closed type, the above-described problems with respect to the open type impeller are solved. Similarly, even in the closed type, since there are no blades, the rigidity is higher than that of a conventional closed type impeller, and there is no fear that the blade tip portion is shaken during operation. Therefore, the problem of vibration and noise is solved.

  Since the cross section of the fluid flow path of the impeller is made circular as in the invention of claim 2, the processing is easy, the inside of the impeller is easy to clean, and no recesses or residues that tend to leave microorganisms are not formed. Particularly suitable for sanitary pumps.

  As in the invention of claim 3, by providing a notch for reducing the outlet angle from the outer end of the fluid flow channel to the outer peripheral surface of the impeller, the angle formed by the fluid flow channel and the outer peripheral surface of the impeller, Since the outlet angle can be reduced, the pump efficiency is good and the power consumption energy is economical.

  As in the invention of claim 4, by providing cylindrical outer peripheral surfaces protruding on both sides in the axial direction of the impeller, the clearance between the corresponding cylindrical inner peripheral surfaces on the casing side is minimized, and the suction pressure is sucked. Pump efficiency can be increased by preventing leakage to the side and maintaining the discharge pressure in the machine. Since such sliding surfaces for holding pressure are arranged on both sides in the axial direction, the rotation balance is good. And since it is cylindrical surfaces parallel to the rotating shaft line of an impeller, it is the structure which can respond also to expansion-contraction of a main axis | shaft.

  By using a dense forged material or rolled material as the impeller material as in the invention of claim 5, there is no rough skin or cast hole peculiar to castings as compared with the case of casting which has been generally used conventionally. Therefore, it is safe and clean (sanitary).

  According to the sixth aspect of the present invention, when the impeller is finished on the entire surface, a smooth surface can be obtained, and a safe impeller for a sanitary pump can be manufactured cleanly. In addition, the balance of the rotating body can be optimized. Although not essential, when implemented in combination with the invention of claim 5, an impeller surface which is dense and hardly collects residue can be obtained, and an impeller suitable particularly for a sanitary pump can be provided.

(A) is a rear view of an impeller, (B) is sectional drawing which follows the BB line of (A). It is a longitudinal cross-sectional view of the principal part of a centrifugal sanitary pump. It is a partial front view of the impeller for demonstrating exit angle | corner (theta), Comprising: (A) is a case with notch, (B) is a case with a notch.

Embodiments of the present invention will be described below with reference to the drawings.
First, the centrifugal sanitary pump will be described with reference to FIG. The illustrated pump is an example of a spiral pump, and includes a casing 10, a main shaft 20, a mechanical seal 30, and an impeller 40. A spiral chamber for accommodating the impeller 40 is formed inside the casing 10, and the spiral chamber is literally spiral, and as the impeller 40 rotates, the axial portion becomes low pressure and the outer peripheral side becomes high pressure. Corresponding to the arrangement of the vortex chamber, the casing 10 includes a suction port 12 coaxial with the rotation axis of the impeller 40 and a discharge port 14 communicating with the high pressure portion.

  The main shaft 20 passes through the casing 10 so as to be rotatable with respect to the casing 10, and is connected to driving means (not shown) such as an electric motor at an end opposite to the screw portion 22 at the tip. Then, when the main shaft 20 is rotated by the driving means, the impeller 40 rotates, whereby the liquid is sucked from the suction port 12 and discharged from the discharge port 14.

  A mechanical seal 30 as a shaft seal device is attached to a portion of the casing 10 through which the main shaft 20 passes. The portion where the shaft seal device is provided is called a stuffing box and is indicated by reference numeral 16 in FIG. The mechanical seal 30 includes a seat ring 32, a driven ring 34, and contact surface pressure applying means 36. The contact surface pressure application means 36 acts to push the driven ring 34 in the axial direction so that the sealed end surface of the driven ring 34 contacts the sealed end surface of the seat ring 32. As the contact surface pressure applying means 36, a compression coil spring, a coiled wave spring, or the like is used. In this way, sealing is achieved by sliding the sealing end surface of the seat ring 32 and the sealing end surface of the driven ring 34 in sliding contact. Since the basic structure of the mechanical seal 30 is well known, detailed description thereof is omitted here.

  A notch recessed in the axial direction from the end surface is provided at the end of the driven ring 34 opposite to the sealed end surface. By inserting the pin 38 implanted in the boss portion of the impeller 40 into this notch, the impeller 40 and the driven ring 34 are prevented from rotating relative to each other, in other words, both rotate together.

  Here, in more detail with reference to FIG. 1, as shown in FIG. 1 (A), the overall appearance of the impeller 40 has a disk shape. In addition, the arrow of FIG. 1 (A) represents a rotation direction. As can be seen from FIG. 1B, the impeller 40 includes a disc portion 42, a pair of protrusions 44 a and 44 b, and a boss portion 46. The protrusions 44a and 44b protrude on both sides in the axial direction of the disk portion 42, and correspond to the cylindrical inner peripheral surfaces 18a and 18b of the casing 10, respectively (see FIG. 2). And the clearance gap between the cylindrical outer peripheral surface of the protrusion 44a and the cylindrical inner peripheral surface 18a of the casing 10, and between the cylindrical outer peripheral surface of the protrusion 44b and the cylindrical inner peripheral surface 18b of the casing 10 By setting the clearance to a predetermined minute value, the discharge pressure is prevented from leaking to the suction side, the discharge pressure in the machine is maintained, and the pump efficiency is improved. Further, since the cylindrical outer peripheral surface on the impeller 40 side and the cylindrical inner peripheral surface on the casing 10 side are cylindrical surfaces parallel to the rotation axis of the impeller 40, even if the main shaft 20 expands or contracts to some extent due to thermal expansion or the like, It is absorbed by the axial displacement between the cylindrical surfaces and interference is prevented.

  A bottomed cylindrical cavity 50 is formed inside the left protrusion 44a of FIG. 1B, and this serves as a suction port for the impeller 40 (also referred to as an impeller eye). The void 50 extends coaxially with the suction port 12 of the casing 10, and the inner peripheral surfaces of both are substantially the same diameter (see FIG. 2). A boss portion 46 is integrally formed on the axial center side of the right protrusion 44 b in FIG. 1B, and the impeller 40 is fixed to the main shaft 20 by this boss portion 46. Specifically, it is positioned in the axial direction by tightening an impeller nut 26 to a screw portion 22 formed at the end of the main shaft 20. By a conventional method, the impeller 40 and the main shaft 20 are coupled so as to be able to transmit torque. The drawing shows an example in which the key 24 is used. The void 50 is opened only on one side (left side in FIG. 1B), and the opposite side (right side in FIG. 1B) is closed. An O-ring seat 48 for the O-ring 28 interposed between the impeller nut 26 and the impeller nut 26 is formed on the end surface of the boss portion 46 corresponding to the closed bottom surface of the space 50.

  As shown in FIG. 2, the suction side is provided with the O-ring 28 at the most liquid contact portion of the joint surface with the impeller nut 26 for fastening the impeller 40, and the male screw portion 22 and the shaft key 24 portion of the main shaft 20 are provided. The structure does not come into contact with liquid. Therefore, there is no liquid pool in detail, the cleaning property is good, and it is hygienic (sanitary property). Similarly, as shown in FIG. 2, the mechanical seal 30 can be directly attached to the boss portion 46 on the stuffing box 16 side. Therefore, a structure in which the shaft 20 does not come into contact with the liquid is realized, there is no liquid pool in details, the cleaning property is good, and it is hygienic (sanitary).

  The disc portion 42 is provided with a plurality of fluid flow paths 52. FIG. 1A shows an example in which eight fluid flow paths 52 are arranged at equal intervals in the circumferential direction. As shown by broken lines, a plurality of fluid flow paths 52 are arranged substantially radially from the void 50. It is. Each fluid passage 52 is linear, and the center line extends in a tangential direction or parallel to the inner peripheral surface of the cavity 50. Each fluid channel 52 opens into the void 50 at the inner end, and opens to the outer peripheral surface of the impeller 40 at the outer end. Since the impeller 40 does not have blades, the impeller 40 has high rigidity as a whole, and there is no fear that the blade tip portion is shaken during operation. By making the cross section of the fluid flow path 52 circular, it is not only easy to process, but also easy to clean, and is not suitable for sanitary pumps because it does not form recesses where residues and microorganisms tend to remain.

  A cutout 54 is provided at the outer end of the fluid flow path 52 by milling. Accordingly, the angle formed between the fluid flow path 52 and the outer peripheral surface of the impeller indicated by the symbol θ in FIG. In the case of the illustrated example, the notch 54 is processed by an end mill and has a substantially elliptical shape when viewed from the outer peripheral side of the impeller. 3A shows the case where there is no notch, and FIG. 3B shows the case where the notch 54 is provided. If a specific example of the outlet angle θ is given, generally the best is about 20 ° to 30 °, but relatively good pump efficiency can be obtained even at about 30 ° to 35 °. As is clear from the comparison between FIG. 3A and FIG. 3B, the exit angle θ can be made closer to the ideal by providing the notch 54.

  The impeller 40 is provided with a through hole 56 called a balance hole. In addition to relieving the thrust load acting on the impeller 40 during operation, this serves to convect the sealing liquid in the stuffing box 16 and improve the cleaning performance.

  As the material of the impeller 40, a dense forged material or rolled material is used. Thereby, compared with the case where it manufactures by casting like before, it is safe and clean (sanitary property). Further, the impeller 40 has an advantage that the balance of the rotating body can be optimized by making the entire surface cut. Of course, the fluid passage is also finished by cutting. Since it has a circular cross section and is linear, it can be easily machined by drilling or milling.

10 Casing 12 Suction port 14 Discharge port 16 Stuffing box 18a, 18b Cylindrical inner peripheral surface (sliding surface)
20 Main shaft 22 Male thread portion 24 Key 26 Impeller nut 28 O-ring 30 Mechanical seal 32 Seat ring 34 Drive ring 36 Contact pressure applying means 38 Pin 40 Impeller 42 Disc portion 44a, 44b Projection portion 46 Boss portion 48 O-ring seat 50 Void 52 Fluid flow channel 54 Notch 56 Through hole (balance hole)

Claims (7)

  In a closed-type impeller provided with a cylindrical suction port in the shaft center part, the inner end portion has a plurality of fluid flow paths that open to the suction port and the outer end portion opens to the outer peripheral surface of the impeller. Each fluid flow path is an impeller for a centrifugal pump that is in a straight line parallel to the tangential direction of the suction port.   The impeller for a centrifugal pump according to claim 1, wherein a cross section of the fluid flow path is circular.   The impeller for a centrifugal pump according to claim 1 or 2, wherein a notch for reducing an outlet angle of the fluid flow path is provided from an outer end portion of the fluid flow path to an outer peripheral surface of the impeller.   The impeller for a centrifugal pump according to claim 1, 2 or 3, further comprising a cylindrical outer peripheral surface protruding on both sides in the axial direction.   The impeller for centrifugal pumps according to any one of claims 1 to 4, wherein the impeller is made of a forged material or a rolled material.   The impeller for centrifugal pumps according to any one of claims 1 to 5, wherein the entire surface is finished by cutting.   A centrifugal sanitary pump equipped with the centrifugal pump impeller according to any one of claims 1 to 6.

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