AU607950B2 - Mechanical seal for a slurry pump - Google Patents

Description

1. i I II

AUSTRALIA

Patents Act COMPLETE SPECIFICATIO 8 0 7

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 8 48 4 t, o 04 o o 000 O 0a 84 8 Priority Related Art: This doctmrnnt cont!'tns tle Ircn~jJT]9t s iad S C Y~-ir dlkP S Cr.C' j: APPLICANT'S REFERENCE: U-8722 Name(s) of Applicant(s): Eagle Industry Co. Ltd.

Address(es) of Applicant(s): 6-15, Shibakoen 2-chome, Minato-ku, Tokyo,

JAPAN.

Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: MECHANICAL SEAL FOR A SLURRY PUMP Our Ref 72672 POF Code: 1342/66191 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 6003q/l 1 L ~e 1 6012q/1 i MECHANICAL SEAL FOR A SLURRY PUMP The present invention relates to an improvement in a mechanical seal used for a shaft seal portion of a slurry pump which feeds under pressure liquids containing a large amount of slurries.

As one example of a slurry pump used to pump up muddy water produced in mining ores for example or to transport muddy water in waste water disposal facilities, a slurry pump has been known in which as shown in Fig. 2, an impeller 3 is mounted on the end of a shaft 2 which extends from a driving source such as a motor i, and upon the rotational operation of the impeller 3, slurry liquids containing a large amount of bauxite, powdery coal, sediments or the like are fed under pressure. A mechanical seal 11 having a function as a shaft seal device is provided in a boundary between an internal space o o S 4 of pump and an external space 5 of pump in order that ooo o said slurry liquids may not be flown from the periphery of o2 0 the shaft 2 to the external space 5 of pump.

o 0 Referring to Fig. 3 the mechanical seal indicated 040000 generally at 11 has a stationary inner sealing ring 12 o oo S airtightly carried on the side of a pump housing 6 and a O 00 rotating outer sealing ring 13 carried on the side of the shaft 2, the sealing rings 12 and 13 axially abutting each other to prevent a slurry liquid S present on the outer diameter side of the abutted portion from passing toward the inner diameter of the abutted portion.

O More specifically, a flange 14 is airtightly secured to the inner peripheral portion of the pump housing 6, and a seal cover 16 is airtightly secured to the outer peripheral portion of the shaft 2 through a sleeve The stationary inner sealing ring 12 is fitted through a resilient inner mounting 17 into an annular recess 14' formed in the opposed portion with respect to the seal cover 16 in the flange 14. The rotating outer sealing ring 13 is fitted through a resilient outer mounting 18 into an annular recess 16' formed in the opposed portion 39.. with respect to the flange 14 in the seal cover 16. The -o' g i- L; '~ii resilient mountings 17 and 18 preferably comprise rubber and are adapted to impart a shaft sealing force as needed due to contact load between both the sealing rings 12 and 13. The resilient inner mounting 17 has projections 17a and 17b formed on both ends thereof in a peripherally equally spaced relation, said projections engaging a notch formed in the annular recess 14' of the flange and a notch formed in the inner sealing ring 12 to effect locking of the sealing ring 12 and also having a packing function for maintaining airtightness between the flange 14 and the sealing ring 12. Likewise, the resilient outer mounting 18 has projections 18a and 18b provided on both ends thereof which engage a notch formed in an annular recess i 18' of the seal cover 16 and a notch formed in the outer sealing ring 13 to transmit torque from the shaft 2 to the V sealing ring 13 and having a packing function for maintaining airtightness between the seal cover 16 and the sealing ring 13.

However, in the present structure the resilient mountings 17 and 18 are directly exposed to the slurry liquid S. Also outer resilient mounting 18 rotates along with the sealing ring 13 and seal cover 16 Therefore the resilient mounting 18 is shaved off by contact with solid matter in the liquid and gradually wears. Consequently the contact load required for sealing between the sealing rings 12 and 13 is impaired.

In view of the foregoing, an object of the present invention is to alleviate wear of the resilient mountings 17 and 18 to prolong their service life.

With this in mind, the present invention provides a mechanical seal for a slurry pump having a housing and a shaft rotatably journalled in said housing, said seal comprising: a stationary inner sealing ring fitted via a first resilient mounting onto a flange secured to an inner peripheral portion of said housing and a rotating outer sealing ring fitted via a second resilient mounting onto a seal cover secured to an outer peripheral portion of said shaft, wherein said inner and outer sealing rings are -3- 0v I -i* disposed in axially abutting relationship relative to one another, and including a flexible seal body extending between said outer sealing ring and said seal cover so as to cover a face of the second resilient mounting exposed to slurry liquid, said seal body being in contact with the seal cover and being mounted on the outer peripheral portion of sair' outer sealing ring.

The flexible seal body extends between the outer sealing ring and the seal cover to prevent solid matter in the slurry liquid from contacting the outer resilient mounting.

The following description refers in more detail to the various features of the mechanical seal of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where tha mechanical seal is illustrated in a preferred embodiment. It is to be S understood that the mechanical seal of the present invention is not limited to preferred embodiment 0°0 illustrated in the drawings.

Fig. 1 is a half sectional view showing the mounted state of a mechanical seal according to an embodiment of the present invention; Fig. 2 is a sectional view showing one example of a slurry pump; and Fig. 3 is a half sectional view showing one example of a conventional mechanical seal.

A mechanical seal shown in Fig. 1 as one embodiment of the present invention is constructed such that in the C mechanical seal 11 of the type shown in Fig. 3, there is >0 bonded or bakedly-fixed to the outer peripheral surface of the outer sealing ring 13 a flexible seal body 19 formed of a material which is excellent in wear resistance. The seal body 19 may comprise a hard urethane or soft plastic which is sufficiently soft so as not to impair the following property of the mechanical seal 11 in response to relative displacement between the housing 6 side and the shaft 2 side. An end of the seal body 19 extends in a tapered fashion toward the outside diameter of the -39> resilient mounting 18 in the form of a lip 20 so as to

LS

Li_(fi -e w __I~II~IIDC~ ii.. yX cover a face of the resilient mounting 18 on the side of the slurry liquid S and is placed in close contact with a front end 16a of a seal cover 16. With this arrangement, entry of solid matter in the slurry liquid S is prevented between the seal body 19 and the resilient mounting 18.

It is to be noted that a flexible seal body can be likewise mounted on the outer peripheral portion of the inner sealing ring 12 in addition to the structure of the above-described embodiment in order to prevent corrosion of the inner resilient mounting 17 resulting from the following wake of the slurry liquid S during rotation.

As described above, according to the mechanical seal for a slurry pump of the present invention, since a seal body is provided on the outer peripheral portion of the outer sealing ring to preve! t corrosion of the resilient mounting caused by solid matter in the slurry liquid, the o:o required load imparted to the sealing rings by the 0 a resilient mountings is retained, thus providing excellent S: :prospects that the service life of the sealing rings may 040 0 .o 20 be prolonged.

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