JPS622318Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a rectifying plate that is provided on the outer periphery of the suction passage on the upstream side of the pump impeller to prevent noise and vibration generated from the pump. .

[Prior art]

For example, when a centrifugal pump is operated in a partial flow range below the maximum efficiency point, a portion of the fluid sucked into the pump impeller is flush with the pump impeller at the outer periphery of the suction passage immediately upstream of the pump impeller. It is known that the phenomenon of reverse flow occurs while turning in the rotation direction, and this causes noise and vibration.

FIG. 1 shows the flow state of such a conventional centrifugal pump. In the figure, a pump impeller 2 is integrally fixed to a rotating shaft 4 by an impeller locking nut 3 in a body 1, and this pump As the impeller 2 rotates, fluid is sucked in from a suction passage 5 defined by the body 1 and discharged into a discharge passage of a volute chamber 6 defined by the body 1.

In such a conventional centrifugal pump, as described above, a vortex is generated at the outer periphery of the suction passage 5 immediately upstream of the pump impeller 2, as indicated by streamlines, causing noise and vibration.

In Fig. 1, 7 is a liner ring, 8 is a liner ring, and 8 is a liner ring.
1 is a gland cover, 9 is a suction flange, 10 is a shaft sleeve, 11 is a gland packing, and 12 is a gasket.

Therefore, as shown in FIG. 2, a ring-shaped aperture plate 20 is provided at the position where this vortex is generated, that is, on the outer periphery of the suction passage 5 immediately upstream of the pump impeller 1, and this aperture plate 20 blocks the vortex. However, techniques for preventing cavitation are known.

However, even if such aperture plate 20 is provided, as shown in FIG. 2, the vortex shown in FIG. 1 is only divided into two, and noise and vibration are still generated.

To this end, the present applicant has proposed a technique in which a baffle plate having porous holes is provided on the outer periphery of the suction passage on the upstream side of the pump impeller, as disclosed in Japanese Patent Application Laid-open No. 113201/1983. However, although this technique is effective to some extent, it has not been able to sufficiently reduce noise and vibration, especially when the energy of the swirling flow generated near the cut-off point from the partial discharge flow rate region is large.

[Purpose of invention]

Therefore, an object of the present invention is to provide a rectifying plate for preventing the generation of pump noise and vibration, which can sufficiently attenuate the energy of the swirling flow generated near the cutoff point from the pump's partial discharge flow rate. .

[Structure of the idea]

According to the present invention, in the rectifying plate provided on the outer periphery of the suction flow path on the upstream side of the pump impeller and for preventing noise and vibration generated from the pump, the rectifying plate is composed of a ring-shaped plate. A hollow ring-shaped diffusion chamber is provided in the chamber, and a large number of holes are formed in both walls of the diffusion chamber on the pump impeller side and the suction port side.

[Function and effect of the idea]

Therefore, even if a vortex is generated at the outer periphery of the suction passage upstream of the pump's impeller, which has relatively large swirling flow energy and causes noise and vibration, the vortex will not flow through the pump in the diffusion chamber. It flows into the diffusion chamber through the opening on the impeller side, and is confined within the diffusion chamber to attenuate the energy of the swirling flow. The liquid flows out from the opening on the pump impeller side together with the liquid that has flowed into the diffusion chamber through the opening on the suction side, is pressurized by the impeller, and is discharged.

Therefore, the swirling energy can be reliably attenuated by the hollow ring-shaped diffusion chamber provided in the baffle plate, and noise and vibration can be prevented.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 3, 4, and 5.

The current plate, which is designated as a whole by reference numeral 30, is the pump impeller 2.
It is provided on the outer periphery of the suction flow path 5 immediately upstream of. The current plate 30 includes a ring-shaped plate 31, and a hollow ring-shaped diffusion chamber 32 is provided at an inner diameter position radially outward of the ring-shaped plate 31. Both walls 32a and 32b of the diffusion chamber 32 on the pump impeller 2 side and the suction port (suction flange 9) side
A large number of openings (including slits) 33 are formed in the opening. Further, it is preferable to provide a large number of protrusions 34, . In this embodiment, the protruding body 34 is a hollow cylinder, but it may have a shape other than a cylinder. In addition, in this embodiment, the pump impeller 2 is located outside the protruding body 34.
A ring-shaped protruding wall 35 is provided that protrudes to the side. However, the protrusion 34 does not necessarily need to be provided when implementing the present invention.

Now, the fluid flowing back from the pump impeller 2 has a very large swirling flow energy and generates vortices that cause noise and vibration as described above. Therefore, in the current plate of the present invention, the axial and circumferential components of the fluid flow through the holes 33, ... (the holes 34a if the protrusion 34 is hollow) and the diffusion chamber 32. This is to attenuate the turning energy.
Further, by providing the ring-shaped protruding wall 35, leakage from the liner ring portion can be caused to flow into the pump impeller 2.

Conventionally, as mentioned above, fluid with a complicated flow was received only by a restrictor plate, but the rectifier plate of this invention attenuates both the axial and circumferential components simultaneously, so the damping effect is extremely large, and the flow is reliable. Prevents the generation of vortices.

Figures 5A and 5B show examples of performance curves for a conventional centrifugal pump and a centrifugal pump equipped with a baffle plate according to the present invention, where the solid line indicates the conventional one and the dotted line indicates the one according to the present invention. . As can be seen from this graph, noise and vibration can be significantly reduced with almost no reduction in pump efficiency.

〔summary〕

As explained above, if the current plate according to the present invention is used, it is possible to reliably prevent the generation of vortices and significantly reduce noise and vibration, and it is particularly effective in preventing noise and vibration near the cutoff point. It is.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the flow when a conventional centrifugal pump is operated in a partial flow rate region. FIG. 2 is a diagram showing the flow when a conventional throttle plate is provided in front of the pump impeller suction inlet to prevent backflow in the partial flow rate region. FIG. 3 is a diagram showing the flow when a rectifying plate according to the present invention is provided to prevent backflow in a partial flow area. Figures 4A and 4B show the details of the rectifier plate in which the present invention is implemented, and A is A of B.
- A sectional view taken along line A;
FIGS. 5A and 5B are graphs showing performance curves of a conventional centrifugal pump and a centrifugal pump equipped with a fluid plate according to the present invention. DESCRIPTION OF SYMBOLS 1... Body, 2... Pump impeller, 5... Suction channel, 6... Volute chamber, 7... Liner ring, 20... Throttle plate, 30... Rectifier plate, 31...
Ring-shaped plate, 32... Hollow ring-shaped diffusion chamber, 33
...Open hole.

Claims (1)

[Scope of utility model registration request] The rectifying plate is installed on the outer periphery of the suction passage on the upstream side of the pump impeller to prevent noise and vibration generated from the pump, and is composed of a ring-shaped plate. A rectifying plate for preventing noise and vibration of a pump, characterized in that a chamber is provided, and a large number of holes are formed in both walls of the diffusion chamber on the pump impeller side and the suction port side.