JP2015040520A - Double suction volute pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double suction volute pump in which a rotary shaft of the pump is shortened by outputting an axial thrust and receiving it between a volute and an impeller and its small-sized and light weight pump is realized by simplifying a structure within a bearing box.SOLUTION: The present invention relates to a double suction volute pump comprising an impeller having partition parts, blades and side plates arranged to suck fluid from both axial sides and discharge it from outer circumferential surfaces; a pump casing having a suction volute forming a fluid suction flow passage for the impeller and a discharging volute forming a fluid discharging flow passage for fluid from the impeller; and a bearing box storing bearings for supporting both ends of the shaft characterized in that there is provided an annular supporting ring fixed to the inner surface in a radial direction of an axis of the discharging volute to which the outer surfaces of the side plates are contacted and slid and a shaft thrust force acting in an axial direction when the impeller is rotated is supported by the supporting ring through the side plates.

Description

  The present invention relates to a double suction centrifugal pump, and more particularly, to a double suction centrifugal pump that is reduced in size and weight and improves pump efficiency.

  A conventional double suction centrifugal pump is shown in FIGS. The both suction centrifugal pumps include an impeller 30 provided with a partition portion 31, blades 32 and blade side plates 33 so as to suck fluid from both sides in the direction of the rotary shaft 7 and discharge the fluid from the outer peripheral surface, and the impeller 30. A pump casing 20 having a suction volute 22 that forms a fluid suction passage for fluid and a discharge volute 21 that forms a fluid discharge passage from the impeller 30, and a discharge facing the suction side end of the side plate 33 And a wear ring member 34 attached to the inner peripheral end face of the sword volute 21. The discharge volute 21 is formed wider in the axial direction than the outer peripheral surface of the impeller 30 in order to enlarge the discharge flow path, and the wear ring member 34 is used when the impeller 30 and the pump casing 20 are in contact with each other. It is provided. In the figure, 8 to 10 are bearings for supporting the rotary shaft 7 of the pump, 8 is a radial bearing on the shaft coupling side, 9 is a radial bearing on the anti-shaft coupling side, and 10 is a thrust bearing on the anti-shaft coupling side.

  In FIG. 5, when the pump casing 20 is manufactured by casting, the gap width between the impeller 30 and the discharge volute 21 is different on the left and right with respect to the axis of symmetry of the cross section of both suction centrifugal pumps due to the allowable manufacturing error of the casting. Sometimes. In this case, in the narrower one, the swirl flow accompanying the rotation of the impeller 30 becomes faster than in the wider one, and the pressure decreases as compared with the larger one. Collapses. Originally, it is a double suction centrifugal pump that is one of the merits that axial thrust (thrust thrust) hardly occurs by making it a symmetrical shape, but it is necessary to design a bearing that supports the above axial thrust. Therefore, the thrust bearing 10 is provided in FIG. For this reason, it has become a factor that the entire pump cannot be reduced in size.

  In order to solve the above-described problem, in Patent Document 1, a wear ring that closes the gap between the discharge volute and the impeller is provided to reduce axial thrust, and in Patent Document 2, it protrudes toward the side plate. A land portion is provided in the casing to suppress axial thrust. However, although the structures shown in Patent Document 1 and Patent Document 2 can both suppress axial thrust, but cannot be completely reduced to 0, the bearing portion includes a thrust bearing. Therefore, in Patent Documents 1 and 2, the thrust shaft is installed, the length of the rotary shaft of the pump is lengthened, and the structure inside the bearing box becomes complicated and large, which is an obstacle to reducing the size and weight of the pump. .

JP 2007-198270 A JP 2011-140916 A

  An object of the present invention is to reduce the size and weight of the pump by shortening the rotary shaft of the pump and simplifying the structure inside the bearing box by discharging axial thrust and receiving it between the volute and the impeller. Another object is to provide a double suction centrifugal pump.

In order to solve the above problems, the present invention provides an impeller in which a partition, a blade, and a side plate are disposed so as to be sucked from both sides in the axial direction and discharged from the outer peripheral surface,
A pump casing having a suction volute that forms a suction passage for fluid to the impeller and a discharge volute that forms a discharge passage for fluid from the impeller; and
A bearing box containing a bearing that supports both ends of the shaft;
In the double suction centrifugal pump in which the discharge volute is formed wider in the axial direction than the outer peripheral surface of the impeller,
A radial bearing for supporting the shaft in the radial direction in the bearing housing;
A liner ring is provided between the suction side end of the side plate and the inner peripheral end surface of the discharge volute,
An annular support ring is provided that is fixed to the radially inner surface of the discharge volute shaft and that the outer surface of the side plate contacts and slides;
A shaft thrust acting in the axial direction when the impeller rotates is supported by the support ring via the side plate.

  Further, in the above-described suction pumps, the discharge volute has an inner surface having a flat portion extending in the radial direction of the shaft, and the support ring is fixed to the flat portion.

  Further, in the above-described suction pumps, the surface of the support ring that is in sliding contact with the side plate of the impeller is made of a material whose hardness is lower than that of the impeller side plate.

  Further, in the above-described suction pumps, the surface of the support ring that is in sliding contact with the side plate of the impeller is inclined.

  Further, in the above-described both suction centrifugal pumps, the support ring has an annular sliding portion that is in sliding contact with a side plate of the impeller.

  Further, in the above-described two suction centrifugal pumps, a step portion is formed on the inner surface of the discharge volute, and the support ring is aligned and fixed to the step portion.

  Further, in the above-described both suction centrifugal pumps, the support ring is fixed to the inner surface of the discharge volute while being prevented from rotating by a pin.

  Further, in the above-described both suction centrifugal pumps, the sliding portion is fixed to the support ring in a state of being prevented from rotating by a pin.

  Further, in the above-described both suction centrifugal pumps, the sliding portion is characterized in that a sliding surface in sliding contact with a side plate of the impeller is inclined.

  Further, in the above-described two-suction centrifugal pump, the support ring has a concave portion formed on the mounting surface of the sliding portion, and the sliding portion is aligned and fixed to the concave portion.

  According to the present invention, it is possible to eliminate a thrust bearing conventionally provided in a bearing box, and to reduce the size and weight of the pump by making the accompanying shaft, bearing box and the like small and simple.

  Further, since the mechanism for receiving the axial thrust is composed of a thrust bearing with a blade side plate and a support ring and installed in water, grease and lubricating oil for lubrication and cooling are not required.

It is sectional drawing which decomposes | disassembles and shows the both suction centrifugal pump of embodiment of this invention. It is sectional drawing which similarly shows the structure of the assembled state of both suction vortex pumps. Similarly, it is sectional drawing which expands and shows the principal part of both suction vortex pumps. It is sectional drawing which decomposes | disassembles and shows the principal part of both suction vortex pumps similarly. It is sectional drawing of the double suction centrifugal pump of a prior art. Similarly, it is sectional drawing which expands and shows the principal part of both suction vortex pumps.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the embodiments and the drawings of the prior art indicate the same or equivalent.

  Both suction centrifugal pumps of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an exploded cross-sectional view of a double-suction centrifugal pump 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a structure of the double-suction centrifugal pump 1 according to the embodiment in an assembled state. FIG. 3 is a cross-sectional view showing an embodiment of the present invention and an enlarged main portion. FIG. 4 is a view showing the embodiment of the present invention and an exploded cross-sectional view showing the main portion. is there.

  1 and 2, reference numeral 8 denotes a radial bearing that is housed in a bearing box 11 on the shaft coupling side and supports the rotary shaft 7 of the pump in the radial direction, and 9 is a housing that is housed in a bearing box 12 on the anti-shaft joint side. It is a radial bearing supported in the radial direction. Each of the bearing housings is provided with only a radial bearing as a bearing. Compared with the prior art, since the thrust bearing is not built in the bearing housing 12 on the anti-shaft joint side in particular, the rotation shaft 7 of the pump is correspondingly increased. The length is shortened, the internal structure is simplified, and it is compact and lightweight.

  The impeller 30 is configured by disposing a partition portion 31, blades 32, and side plates 33 on both sides in the axial direction so as to be sucked from both sides in the axial direction and discharged from the outer peripheral surface. The partition part 31 is located in the axial center part of the impeller 30, and is formed in the disk shape extended to radial direction outward. A plurality of blades 32 are provided in the circumferential direction on both sides of the impeller 30. The side plate 33 is provided on the side surface of the blade 32 in a conical ring shape, and the discharge side end extends in the radial direction of the shaft.

  The pump casing 20 includes a discharge volute 21 that forms a discharge passage for fluid from the impeller 30 and a suction volute 22 that forms a suction passage for fluid to the impeller 30. The discharge volute 21 is formed to be wider in the axial direction than the outer peripheral surface of the impeller 30 in order to enlarge the discharge flow path, and is formed to cover the side surface of the impeller 30. Two suction volutes 22 are formed on both sides of the discharge volute 21 so as to surround the suction port of the impeller 30.

  The pump casing 20 is made of a casting because the cross-sectional shape of the discharge volute 21 is a complicated three-dimensional shape that continuously changes from the start of winding of the volute to the discharge port. Used as is.

  The rotary shaft 7 passes through the central portion of the partition portion 31 of the impeller 30 and is fixedly attached to the impeller 30, and is supported by brackets 25 provided on both sides of the pump casing 20. That is, the bracket 25 supports the bearing housings 11 and 12, the bearing housings 11 and 12 incorporate the bearings 8 and 9, and the bearings 8 and 9 support both ends of the rotating shaft 7 in the radial direction.

  As shown in FIG. 1, the pump casing 20 is formed by casting in the upper and lower parts, and a structure composed of the shaft 7, the impeller 30, and the bearing boxes 11 and 12 is provided between the two parts of the pump casing 20. It is sandwiched and moved in the direction of the arrow and assembled by screwing. FIG. 2 shows the structure of the double suction centrifugal pump 1 assembled as described above.

  Reference numeral 23 denotes a pair of annular support rings fixed to the inner surfaces of both sides in the axial direction of the discharge volute 21. Each support ring 23 is fixed to the inner surface of each discharge volute 21 in a two-divided state (in an arc shape) in the two-divided state of the pump casing 20 in FIG. 1, and the two-divided pump casing 20 is assembled. Sometimes it is configured in a ring.

  Specifically, as shown in FIG. 4, each of the support rings 23 is fixed to the inner surface of both sides in the axial direction of the discharge volute 21 and to a flat surface portion 21 b extending in the radial direction of the shaft 7. As shown in FIGS. 2 and 3, the pair of support rings 23 are arranged so as to be in contact with the outer surfaces of the side plates 33 of the blades 32 on both sides sandwiched from both sides in a state where both suction centrifugal pumps 1 are assembled. Has been. When the blade 32 rotates, the outer surfaces of the side plates 33 slide on the surfaces of the pair of support rings 23.

  Thus, since the blades 32 on both sides slide on the surfaces of the pair of support rings 23 when the impeller 30 rotates, the axial thrust in the direction of the shaft 7 received from the fluid on the blades 32 by the rotation is one pair. Supported by a support ring 23. That is, the blades 32 on both sides and the pair of support rings 23 act as thrust bearings that receive axial thrust. Further, since the support ring 23 and the side plate 33 are always in sliding contact with each other, a narrowed portion is formed, and a certain degree of sealing action can be achieved with this narrowed portion.

  34 is a liner ring that is attached to the inner peripheral end surface of the discharge volute 21, is arranged so as to contact the suction side end of each side plate 33 of the blade 32, and the side plate of the blade 32 as the impeller 30 rotates. 33 slides on the surface of the liner ring 34 and rotates, and the liner ring 34 and the side plate 33 form a seal structure.

  The configuration and fixing structure of the support ring 23 will be described in more detail. In FIG. 4, a stepped portion 21a is provided on the inner surface of both sides of the discharge volute 21, a flat portion 21b extending in the radial direction of the shaft 7 is formed, and a fixing hole 21c is formed in the flat portion 21b.

  The support ring 23 includes an annular base portion 23a and an annular sliding portion 23b fixed to the tip of the base portion 23a. The base portion 23a is provided with a pin 23c for fixing to the flat surface portion 21b at the rear end, an annular recess 23g at the tip, and a fixing hole 23e for the annular sliding portion 23b provided in the recess. ing. A fixing pin 23d protrudes from the rear end of the sliding portion 23b, and has a sliding surface 23f that contacts each side plate 33 of the blade 32 at the tip. The sliding portion 23b is formed such that the lower surface width l is smaller than the upper surface width L (L> l), and the upper end of the sliding portion 23b is fixed to the side plate 33 when the support ring 23 is fixed to the flat surface portion 21b of the discharge volute 21. The sliding surface 23f is inclined downward so that it approaches and the lower end moves backward from the side plate 33.

  When fixing the support ring 23 to the flat surface portion 21b of the discharge volute 21, while fixing the support ring 23 to the stepped portion 21a, the fixing pin 23c is press-fitted into the fixing hole 21c, and the sliding portion 23b is inserted into the recess 23g. In the state in which is fitted, the fixing pin 23d is press-fitted into the fixing hole 23e and fixed. Fixing with these fixing pins also acts as a detent for the base portion 23a and the sliding portion 23b.

  With the support ring 23 fixed to the discharge volute 21, a structure composed of the shaft 7, the impeller 30 and the bearing boxes 11 and 12 is sandwiched between the two pump casings 20 as shown in FIG. Thus, the suction pump is assembled by moving in the direction of the arrow. At this time, in accordance with the movement in the direction of the arrow, the outer surface of each side plate 33 of the blade 32 approaches the corresponding support ring 23 and is in contact with each pair of support rings 23 so as to expand in the axial direction. Both suction centrifugal pumps are assembled.

  In the present embodiment, each sliding surface 23f is inclined downward so that the upper end of the sliding surface 23f of each support ring 23 approaches the side plate 33 and the lower end retracts from the side plate 33. When the outer surface of each side plate 33 approaches and contacts each corresponding support ring 23, the lower end of the sliding surface 23 f does not collide with the side plate 33. Accordingly, the blade 32 is disposed at the assembly position shown in FIG. 3 in a state in which the outer surface of the side plate 33 is smoothly guided while being in contact with the sliding surface 23f and is in contact with the support ring 23 in an axial direction. The That is, when the pump is assembled, the sliding surface 23 f of the support ring 23 serves as a guide member for the side plate 33.

  The base portion 23a is made of stainless steel, and the sliding portion 23b is made of a resin whose hardness is lower than that of the blade 32. When the resin is used in this way, when the blade 32 is made of stainless steel, only the resin is worn by sliding, so that only the sliding part 23b needs to be replaced when replacing parts due to wear.

  When the side plate 33 of the blade 32 and the support ring 23 act as a thrust bearing that receives axial thrust, the diameter of the support ring 23 is larger than the diameter of the conventional thrust bearing disposed at the tip of the shaft. Will be dispersed and added to the support ring 23, and the wear of the sliding portion 23b will be extremely small, and the life of the sliding portion can be extended.

  In the present embodiment, the mechanism (thrust bearing) that receives the axial thrust force is constituted by the side plate 33 of the blade 32 and the support ring 23. Therefore, the opposite shaft coupling side (the tip end side of the shaft) of the conventional double suction centrifugal pump shown in FIG. The components such as the thrust bearing 10 and the bearing nut installed in the bearing box are not required, and the structure of the bearing box can be reduced in size and weight. And since the thrust bearing in a bearing box becomes unnecessary, the rotating shaft of a pump can be shortened and the pump can be reduced in size and weight.

  In addition, in the conventional double suction centrifugal pump, grease and lubricating oil are used to lubricate and cool the bearing, but in this embodiment, the blades 32 and the support ring 23 constituting the thrust bearing are in flow. Since it is installed in water, grease and lubricating oil for lubrication and cooling are not required.

  Further, in the present embodiment, the diameter of the blade 32 and the support ring 23 constituting the thrust bearing is larger than the conventional one and the contact area is also increased, so that the axial thrust per unit area at the contact portion is reduced, Wear on the thrust bearing is extremely low.

  In the present embodiment, a double seal structure is formed by the narrowed portion formed by the support ring 23 and the side plate 33 and the seal structure formed by the liner ring 34 and the side plate 33. It is possible to reduce the leakage flow that hinders an ideal flow in which all of the fluid discharged from the nozzle is discharged and discharged through the volute.

  Furthermore, when assembling both suction centrifugal pumps, the support ring 23 guides the side plate 33 as a guide member and smoothly guides it to a stable contact position between the support ring 23 and the side plate 33, and the assembly work becomes easy. The contact state between the support ring and the side plate 33 is also kept good.

  The present invention is a centrifugal pump that employs a structure that replaces a conventional bearing that receives axial thrust, and can be used immediately in the industry.

DESCRIPTION OF SYMBOLS 1 Double suction vortex pump 7 Axis, rotary shaft of pump 8 Radial bearing on shaft joint side 9 Radial bearing on anti-shaft joint side 10 Thrust bearing on anti-shaft joint side 11 Bearing box on shaft joint side 12 Bearing box on anti-shaft joint side 20 Pump casing 21 Discharge Volute 21a Stepped Part 21b Flat Part 22 Suction Volute 23 Support Ring 23a Base Part 23b Sliding Part 23c Pin 23d Pin 23f Sliding Surface 23g Concave 30 Impeller 32 Blade 33 Blade Side Plate 34 Liner Ring

Claims (10)

An impeller having a partition, blades and side plates disposed so as to be sucked from both sides in the axial direction and discharged from the outer peripheral surface;
A pump casing having a suction volute that forms a suction passage for fluid to the impeller and a discharge volute that forms a discharge passage for fluid from the impeller; and
A bearing box containing a bearing that supports both ends of the shaft;
In the double suction centrifugal pump in which the discharge volute is formed wider in the axial direction than the outer peripheral surface of the impeller,
A radial bearing for supporting the shaft in the radial direction in the bearing housing;
A liner ring is provided between the suction side end of the side plate and the inner peripheral end surface of the discharge volute,
An annular support ring is provided that is fixed to the inner surface of the discharge volute and slides in contact with the outer surface of the side plate,
A double suction centrifugal pump characterized in that axial thrust acting in the axial direction when the impeller rotates is supported by the support ring through the side plate. The double suction centrifugal pump according to claim 1,
The double suction centrifugal pump characterized in that the discharge volute has a flat surface portion extending in the radial direction of the shaft on the inner surface, and the support ring is fixed to the flat surface portion. The double suction centrifugal pump according to claim 1 or 2,
The double suction centrifugal pump characterized in that the support ring is made of a material having a lower surface hardness than the impeller side plate in sliding contact with the side plate of the impeller. In both the suction spiral pumps in any one of Claims 1-3,
A double suction centrifugal pump characterized in that the support ring is inclined at a surface in sliding contact with a side plate of the impeller. In both the suction centrifugal pumps in any one of Claims 1-4,
The suction ring centrifugal pump according to claim 1, wherein the support ring has an annular sliding portion that is in sliding contact with a side plate of the impeller. In both the suction centrifugal pumps in any one of Claims 1-5,
The suction volute has a stepped portion on the inner surface, and the support ring is aligned and fixed to the stepped portion. In both the suction vortex pumps in any one of Claims 1-6,
The double suction centrifugal pump, wherein the support ring is fixed to the inner surface of the discharge volute while being prevented from rotating by a pin. In both the suction vortex pumps in any one of Claims 5-7,
The double suction centrifugal pump, wherein the sliding portion is fixed to the support ring in a state of being prevented from rotating by a pin. In both the suction vortex pumps in any one of Claims 5-8,
A double suction centrifugal pump characterized in that the sliding portion is inclined at a sliding surface that comes into sliding contact with a side plate of the impeller. In both the suction vortex pumps in any one of Claims 5-9,
The support ring has a concave portion formed on a mounting surface of the sliding portion, and the sliding portion is fixed in alignment with the concave portion.

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