AU619522B2

AU619522B2 - Mechanical seal for a slurry pump

Info

Publication number: AU619522B2
Application number: AU29960/89A
Authority: AU
Inventors: Yoichi Ogata
Original assignee: Eagle Industry Co Ltd
Current assignee: Eagle Industry Co Ltd
Priority date: 1988-05-30
Filing date: 1989-02-15
Publication date: 1992-01-30
Anticipated expiration: 2009-02-15
Also published as: AU2996089A; JPH01173573U; JPH0615168Y2

Description

i l

AUSTRALIA

Patents Act COMPLETE SPECIF?

(ORIGINAL

619522 Int. Class Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: APPLICANT'S REFERENCE: U-88010 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 ORML3NDE 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 119855 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/1 1 lA- The present invention relates to an improvement in a mechanical seal used for a shaft seal part of a slurry

I

9e*t Is I 1 9* II p. pe 0 9 9* 0 9999 9 9 04 9 9e 9 p 9

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I 9 99 9 9 9 0* 9* 9 C C 9t p.

Ce C Cel1O C t i pump for feeding under pressure liquids containing a large amount of slurries.

One example of a slurry pump used for pumping-up sanitary drain generated during the mining of ore, for example, and for transporting sanitary drain in sanitary-drain treating facilities has been known in which as shown in FIG.

2, an impeller 3 is mounted on the end of a shaft 2 extending 4< from a driving source such as a motor i, and the impeller 3 is rotated and operated to thereby feed under pressure I slurry liquids containing a large amount of bauxite, coal powder, sediments or the like. There is provided a mechanical seal 11 serving as a shaft seal device in a boundary between a space 4 within the pump and a space externally of the pump so that the slurry liquids may not flow out into the space 5 externally of the pump where said motor 1 is installed from and around the shaft 2.

The mechanical seal generally indicated at 11 has a seal ring 22 on a stationary side airtightly carried on the side of a pump housing 6 and a seal ring 23 on a rotational S 0 side carried on the side of the shaft 2, as shown in FIG. 3, and both the seal rings 22 and 23 are axially opposed to each other so as to prevent a passage of the slurry liquid S which is present on the side of the outside diameter of an opposing portion 24 in the direction of the inside diameter 2 r of the opposing portion 24.

More specifically, a flange 15 is airtightly secured to the inner periphery of the pump housing 6 and a seal cover 17 is airtightly secured to the outer periphery of the shaft 2 through a sleeve 16. The seal ring 22 on the i stationary side is mounted through a rubber spring 18 on an annular recess 15' formed in a portion opposed to the seal cover 17 in the flange 15 whereas the seal ring 23 on the rotational side is mounted through a rubber spring i 19 on an annular recess 17' formed in a portion opposed to the flange 15 in the seal cover 17. The rubber springs *08 S 18 and 19 are provided to apply a contact load between both the seal rings 22 and 23 required as a shaft sealing force and concurrently serve as a packing for retaining an airtightness between the flange 15 and the seal ring 22 and between So pp the seal cover 17 and seal ring 23.

The seal rings 22 and 23 are composed of annular sliding members 22a and 23a formed of SiC (silicon carbide), tI f and retainers 22b and 23b made of metal such as steel shrini kage fitted so as to cover the end surface on the side opposite the opposing portion 24 of the annular sliding members 22a and 23a and the outer peripheral surface, the retainers 22b and 23b being formed, in the shape of a recess, at the rear end with engaging portions 22c and 23c with respect to a knock pin 20 axially stood upright on the flange 3 4on the stationary side or with respect to a drive pin 21 axially stood upright on the seal cover 17 on the rotational si.de.

I:

ii Vj ~t r Qo However, according to the mechanical seal having the above-described conventional construction, in both the seal rings 22 and 23, the outermost diameter portions 22b' and 23b' of the retainers 22b and 23b which fasten and hold the annular sliding members 22a and 23a from their outer peripheries expose from the rubber springs 18 and 18 to the space 4 internally of the pump, and become corroded or worn out, and therefore, the seal rings cannot withstand an internal stress generated due to the shrinkage fitting with the annular sliding members 22a and 23a and remained in the aforesaid portions 22b' and 23b', resulting in a possible breakage.

In the case where the entire seal rings 22 and 23 are formed of the SiC, the corrosion resistance and wear resistance with respect to the slurry may be enhanced but since.the SiC is a brittle material, there poses a problem in that damages such as a crack, a breakage or the like tend to occur in the engaging portions 22c and 23c which may contact with the knock pin 20 or drive pin 23 to receive a high torque and a vibration.

4 The present invention provides a mechanical seal for a slurry pump having a construction in which a seal ring on a stationary side mounted through a rubber spring on a flange secured to an inner periphery of a slurry pump housing and a seal ring on a rotational side mounted through a rubber spring on a seal cover .secured to an outer periphery of a rotational shaft inserted into said housing are provided opposedly to each other wherein said seal rings are composed of annular sliding members made of SiC and located so as to be in contact with slurry liquids and retainers made of metal shrunk to fit said annular sliding members and located so as to be not in contact with the slurry liquids, each said retainer including a portion on which said rubber spring is secured, said retainers having engaging portions for engagement with the stationary or the rotational side.

4a S The present- invention provides A mecbhanic1 p-1 having a construction in which a seal ring on a statio nry side mounted through a rubber spring on a flange se red to an inner periphery of a slurry pump housing a a seal ring on a rotational side mounted through a r er spring on a seal cover secured to an outer peri ery of a rotational shaft inserted into said housin are provided opposedly to each other, wherein the se a/rings are composed of annular sliding members made £SiC, and retainers made of metal S, positioned on the /de not in contact with liquid including a portion in ssure contact with the rubber spring in said rings a shrinkage-fitted with respect to said annular j slidi g members and having engaging portions with the *I I tl ationary side or the rotational side.

With the above-described arrangement, in the seal I rings, only the annular sliding members formed of SiC having the slurry resistance are exposed into the space internally hof the pump from the rubber spring having a function as a packing and come into contact with the slurry liquid but the metallic retainers will not contact with the liquid.

Therefore, the corrosion or wear due to the slurry can be prevented, and since the engaging portions with respect to i* the stationary side or rotational side are not formed of i SiC, no crack or breakage occurs.

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, Ii reference is made in the description to the accompanying drawings where the mechanical seal is illustrated in a 3 O preferred embodiment. It is to be understood that the mechanical seal of the present invention is not limited to the preferred embodiment as illustrated in the drawings.

FIG. 1 is a half-sectional view showing the mounting state of a mechanical seal according to one embodiment of the present invention; FIG. 2 is a partial sectional view showing one example of a slurry pump; and FIG. 3 is a half-sectional view showing the mounting I state of a conventional mechanical seal.

JM

r 5f9- In this mechanical seal, seal rings 12 and 13 on a stationary side and a rotational side, respectively, are composed of annular sliding members 12a and 13a approximately 0~t4 a a a.

a *400 4.

p.

4 p 00 4 04 0 0 e *4 0 0~ 00 4 a o~ 0 0 0 *4 4. a 0* *0 *0 00 0 004 04*400 4 0 in the shape of L in section opposed to each other, said annular sliding members being formed of SiC excellent in withstanding properties (corrosion resistance and wear resistance) with respect to bauxite slurry or the like, and retainers 12b and 13b made of metal such as steel shrinkage-fitted to the end opposite to an opposing portion 14 between said annular sliding members 12a and 13a, said retainers having engaging portions 12c and 13c in the form of recesses between a knock pin 20 stood upright on a flange 1 15 on a stationary side and a dry pin 21 stood upright ona seal cover 17 on a rotational side. Rubber springs 18 and 19 adapted to press both the seal rings 12 and 13 to apply a load required for the shaft sealing in said opposing portion 14 have their inner peripheral portions in pressure contact with the annular sliding members 12a and 13a, and the retainers 12b and 13b are present completely externally of an internal space 4 of a pump sealed by the opposing portion 14 and the rubber springs 18 and 19 so that the retainers are not in contact with the slurry liquid S. Accordingly, cO the retainers 12b and 13b are not corroded or worn due to the slurry liquid S, and since the engaging portions 12c and 13c are formed of metal such as steel, they are not damaged or broken due to the contact thereof with the knock pin 20 and the drive pin 21. Furthermore, outer peripheral surfaces of the retainers 12b and 13b are made to be larger 6 in diameter than those of the annular sliding members 12a and 13a in pressure contact with the rubber springs 18 and 19 to thereby form differences in level 12d and 13d, and therefore, the rubber springs 18 and 19 are not deviated due to the pressure of the slurry liquid S.

It is to be noted that the retainers 12b and 13b may be extended so as to form pressure contact surfaces with the inner peripheral surfaces of the rubber springs 18 and 19.

As described above, in the mechanical seal for a Sslurry pump according to the present invention, the seal rings have the annular sliding members made of SiC having the slurry resistance which are merely in contact with the slurry liquid. Therefore, the corrosion and wear of the 8 metal retainers having the engaging portions with the statinary and rotational sides will not occur and the crack and breakage in the engaging portions will not occur as in the case where the entire seal is made of SiC, thus providing an excellent durability.

7

Claims

1. A mechanical seal for a slurry pump having a consztruction in which a seal ring on a stationary side mounted through a rubber spring on a flange secured to an inner periphery of a slurry pump housing and a seal ring on a rotational side mounted through a rubber spring on a seal cover secured to an outer periphery of a rotational shaft inserted into said housing are provided opposedly to each other wherein said seal rings are composed of annular sliding members made of SiC and located so as to be in contact with slurry liquids and retainers made of metal shrunk to fit said annular sliding members and located so as to be not in contact with the slurry liquids, each said retainer including a portion on which said rubber spring is secured, said retainers having engaging portions for i engagement with the stationary or the rotational side.

2. A mechanical seal according to claim 1 substantially as herein particularly described with respect to what is shown in the accompanying drawings. t DATED: 30 October 1991 PHILLIPS ORMONDE AND FITZPATRICK Attorneys for: EAGLE INDUSTRY CO. LTD. 1839Z inO o c-8- NY M_-J