AU601744B2 - Mechanical seal for a slurry pump - Google Patents

Description

:1

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class $'017*1 4 4 Int. Class Applicationa Ntumber: Lodged: Complete Specifica' 'rn Lo( ed: Accepted: Published: Priority ar Lid f uY r 00 0 0 Related Art: 0 0 APPLICAN~T'S REFERENCE: U-8702 0 0 00 0 00 Name(s) of Applicant(s): 0

C

a 0 Eagle Industry Co. Ltd.

0 Address(es) of Applicant-s): 0 6-15, Shibakoen 2-chome, 0.Mi nato -ku, 0' Tokyo,

JAPAN.

Address for Service is: 0o PHILLIPS ORMONDE 'ITZPATRIC( Patent and Trade Mark .4ttorneys 367 Collins Street Aelbourne 3000 AUSTRALIA Complete Specification for the invention entitled: MECHIANICAL SEAL FOR A SLURRY PUMP Our Ref i 56396 POF Code: 1342/66191 The following statement is a full description of this invention, including the best method of performing it Lnuwu to applicant(s): GOD3q/1 1 I The present invention relates to an improvement in a mechanical seal used for a shaft seal part of a slurry pump adapted to pump liquids containing a large amount of slurries.

(Prior Art) One example of slurry pump of this kind has been heretofore known, in which as shown in FIG. 2, an impeller 3 is mounted on the extreme end of a shaft 2 extending from a drive source such as a motor 1, and the impeller 3 is 0 rotated and actuated to pump a slurry liquid containing a pt~C\.ritL'(Cht( S *QcS. o^ large amount of1bauxite or powdery coal. A mechanical seal 11 which functions as a shaft seal device is provided in the boundary between a space 4 on the side of the impeller 3 and a space 5 on the side of the motor 1 so as tolp esaid slurry liquid from flowing towards the motor 1.

The mechanical seal generally indicated at 11 has as shown in FIG. 3, a non-rotational seal ring 12 airtightly carried on the side of a pump housing 6 and a rotational seal ring 13 carried oft said shaft 2, both the seal rings 12 and 13 being axially opposed to prevent the passage of the slurry liquid S present on the outside diameter side with said opposed portion directed towards the inside diameter.

The rotational seal ring 13 is embraced by a holder 14 so that the former may be formed integral therewith. On the other hand, a seal cover 16 is fitted in the outer periphery .y -2- A

NJ

V1

I

of the shaft 2 through a sleeve 15. This seal cover 16 is provided with an axially projecting annular projection 16a on the outside diameter edge on one axial end, a rubber spring 17 is fitted into the inside diameter side of said annular ho\We projection 16a, and said ho.i4 14 is fitted into said rubber spring 17. The holder 14 has a notch 14a form d at the rear end thereof so as to engage a pin 18 projected on the seal cover 16, and is rotated following the shaft 2. The rubber spring 17 is provided, as its name imparts, to back up the ,'lO holder 14 to bias the rotational seal ring 13 against the 0,0l non-rotational seal ring 12.

The non-rotational seal ring 12 is likewise embraced by the holder 19. A flange indicated at 20 is mounted on a pump housing, and a rubber spring 21 is interposed between the flange 20 and the holder 19. The holder 19 is stopped by means of a pin 22.

(Problom intended- t be solv r h zthp invpntinn) In the above-described mechanical seal, the annular projection 16a projected on the forward en' of the seal cover 16 is set so as to satisfy the relation of L 1i, where L is the projected length and Z1 is the length of the surface in abutment with the rubber spring 17; the anaular projection 16a being axially projected from the rubber spring 17 by the length 2 L and an annular space 23 in the form of a depression is formed in the inside diameter side.

3

.J

J-i With this arrangement, when the slurry liquid S is pumped as the pump operates and a part thereof moves around the mechanical seal 11, a part of the slur7y contained in the slurry liquid S is accummulated on an annular space 23.

The slurry liquid S flows rightwards as viewed in the drawing, impinges upcn the tapered surface 6a of the pump housing 6, circulates counterclockwise and leaves the slurry in the annular space 23. The thus left slurry is jumped and rolled Swithin the space 23, and is urged particularly against the annular projection 16a to wear the inside diameter surface of the projection 16a. The present invention has its object to prevent such a wear.

(Mo@ang uccd to olv" the problem)---- S:-Ae---G-hani o..al in th fom uf anLL eLint fluw type mechanical seal according to the present invention comprises an axially projecting annular proje'tion formed in the end of a seal cover fitted into a shaft of a slurry pump, a rubber spring fitted on th side of the inside diameter of said annular projection, a eal ring on the rotational side rotating following e shaft, said seal ring being fitted into said rubber spry g, and the forward end of the seal ring on the rotationl side opposed to a seal ring on the nonrotational ide being projected axially from t;he forward end of sa annular projection, characterized in that the approxi- .mnapely whole surfiace of t-he inide di am-eer i,,rfare of aii d 4

A

Summary of the Invention According to the present invention, there is provided a mechanical seal device for a slurry pump having an impeller rotatable, within a housing on a drive shaft; the seal device being of annular form and adapted to be received on the shaft, to provide a seal between the shaft and housing, with a first one of axially opposed ends of the seal device nearer to the impeller and downstream from its other end with respect to slurry flow under the action of the impeller; the seal device having axially opposed seal rings of which one ring nearer to the other end of said device is non-rotatable and the other ring nearer the first end is rotatable; the seal device further including, between the one end thereof and the other ring, a seal cover connectable to the shaft and by which the other ring is rotatable, an annular projection extending axially from .o the cover towards the other end of the device, and a tirubber seal member fitted radially within the projection r around said other ring; said projection and seal member at the axial ends thereof nearer to the other end of the device together defining a frusto-conical surface which tapers outwardly and away from the other end of the device such that, in use of said device, circulation of slurry to said impeller substantially without accumulation of slurry between said projection and seal member is facilitated.

S cc;

I

I 0I L 1B 39 m- -4a-

AB

respect to said rubber spring to dgE-ie the projecting length thereof, and tapered surf s are formed on the extreme end of said annular Jdection as needed so as to facilitate the circula n of a slurry liquid as a lnir -to hbe an- (Operation) That is, the mechanical seal according to the present invention is designed to eliminate the aforesaid annular space so as not to create the accumulation of slurries contained 310 in slurry liquids flowing into the outer periphery of the S mechanical seal, and more specifically, the projected length of the annular projection is reduced to a the extent of L k1' Thereby all the slurries contained in the liquids ride on the whirling current to flow away, and the inner periperal portion of the annular projection will not be worn.

First, the mechanical seal of the present invention shown in FIG. 1 is compared with the prior art shown in FIG. 3.

In the mechanical seal according to the present invention, an eaeurklprojection 16a projected on the forward end of a 20 arnl o seal cover 16 is shortened 4i4l the approximately whole surface of the inside diameter surface thereof forms a surface in abutment with respect to a rubber spring 17, and a convergent tapered surface 16b is formed in the extreme end of the annular projection 16a. In contrast to the tapered surface 16b, a continuous tapered surface 17a is also formed in the edge of the rubber spring 17.

The slurry liquid flown in from the rightward whirlr very smoothly as shown and carries away the slurry by its own force.

(Effects of the Invention) As described above, in the mechanical seal for the slurry pump according to the present invention, the projected length of the annular projection is defined to eliminate the 10 annular space which is an obstacle of the whirling of the slurry liquid, thereby restraining the accumulation of slurry to prevent a wear of said projected portion. A suitable tapered surface is formed at the extreme end of the projection to make the flow of slurry smoother.

4. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a half sectional view showing the mounted state of a mechanical seal according to the embodiment of the present invention; FIG. 2 is a sectional view of essential parts showing one example of a slurry pump; and FIG. 3 is a half sectional view showing one example of a mechanical Sf seal of prior art.

motor, shaft, impeller, spaces, pump housing, (11) mechanical seal, (12) non-rotational seal ring, (13) rotational seal ring, (14) (19) holders, 6 sleeve, (16) seal cover, (16a) annular projection, (6a)(16b)(17a) tapered surfaces, (17)(21) rubber springs, (18)(22) pins, (20) flange, and slurry liquid.

-7-

Claims (2)

1. A mechanical seal device for a slurry pump having an impeller rotatable, within a housing on a drive shaft; the seal device being of annular form and adapted to be received on the shaft, to provide a seal between the shaft and housing, with a first one of axially opposed ends of the seal device nearer to the impeller and downstream from its other end with respect to slurry flow under the action of the impeller; the seal device having axially opposed seal rings of which one ring nearer to the other end of said device is non-rotatable and the other ring nearer the first end is rotatable; the seal device further including, between the one end thereof and the other ring, a seal cover connectable to the shaft and by which the other ring is rotatable, an annular projection extending axially from the cover towards the other end of the device, and a rubber seal member fitted radially within the projection around said other ring; said projection and seal member at 20 the axial ends thereof nearer to the ccher end of the device together defining a frusto-conical surface which tapers outwardly and away from the other end of the device such that, in use of said device, circulation of slurry to said impeller substantially without accumulation of slurry between said projection and seal member is facilitated.

2. A mechanical seal according to claim 1, substantially as herein before described with reference to the accompanying drawings. DATED: 27 JUNE, 1990 PHILLIPS ORMONDE FITZP IC Attorneys For: f EAGLE INDUSTRY CO. LTD. I 1538Z *1