Mechanical seal with radially disposed bias component

A mechanical seal assembly disposed within a pump housing for retarding the flow and leakage of fluids and other matter from being pumped along the motor drive shaft. The mechanical seal assembly of the present invention includes a non-rotating seal ring and a seal ring which rotates with the motor drive shaft. The non-rotating seal ring is resiliently mounted from the impeller side of the housing and is operably carried by the pump housing such that its seal face is urged toward the seal face of the rotating seal ring. A flexible assemblage comprises part of the non-rotating seal mounting arrangements and assures flexibility of the non-rotating seal face despite pump operating conditions.

FIELD OF THE INVENTION 
The present invention relates to pumps, and more particularly to mechanical 
seals for pumps. 
BACKGROUND OF THE INVENTION 
A conventional mechanical seal used between a motor and a product pump 
includes a stationary seal ring usually connected to the motor housing and 
a rotatable seal ring operably connected to the motor shaft. Each seal 
ring is provided with a lapped seal face opposing the seal face of the 
other ring thereby establishing a dynamic fluid tight seal therebetween. 
Resilient means such as coil springs or bellows urge one seal ring face 
toward the other in a sealing relation. 
Most mechanical seals of the type described have a number of metal parts, 
such as the coil springs or bellows which are exposed to the pump fluid. 
In pumps wherein precipitates are emersed or included in the pump fluid, 
the precipitate matter readily accumulates and hardens about the seals and 
associated mounting parts and presents unique problems. That is, because 
of manufacturing tolerance buildup and other factors, the seal ring faces 
must be permitted a degree of flexure relative to one another during pump 
operation. The brittle-hard precipitate buildup around and about the seals 
and their mounting assembly, however, quickly immobilizes the seal faces. 
Accordingly, deterioration of the seal surfaces usually occurs and the 
seal fails. 
In Baumler et al, U.S. Pat. No. 3,269,738 a glide ring seal for use with a 
rotary piston motor is disclosed. This patent describes the use of a 
disk-type spring for pressing a glide ring into an operative position. 
Unlike the present invention, however, the Baumler et al reference is 
silent concerning a method and means for mounting the seal assembly in a 
balanced state from the impeller side of the housing and through axially 
adjustable means. 
In Voytek, U.S. Pat. No. 3,272,519 seals for use between rear wheels of a 
tractor and a tractor frame are described. Each seal uses a pair of 
elastomeric "rounded square" cross section, sealing elements for urging a 
pair of seal rings toward one another. During use, the elastomers are 
stressed and deform to a diamond shape. Such action leaves crevices at the 
concave grooves into which the elastomeric members are received to collect 
debris. 
The Pechiney Company of France has also developed a seal called the 
"Cefilac" seal. Unlike the present invention, the Pechiney device has a 
resiliently mounted rotating seal assembly. As a skilled artisan will 
appreciate, the resilient mounting of the rotary seal requires that the 
static seal must be arranged with unerring accuracy with respect to the 
drive shaft. In such construction, the sealant assembly is not 
retrofittable to the pump. Instead, various pump parts must be machined to 
accept the Cefilac seal. As mentioned, such parts must be machined with a 
great degree of precision. Such a tolerance relationship is difficult to 
establish and even harder to maintain when seal replacement is required. 
SUMMARY OF THE INVENTION 
Because of the above, the present invention provides a balanced mechanical 
seal which is retrofittable and is constructed for use with pumps adapted 
to move abrasive slurry or fluid having precipitate matter therein. The 
mechanical seal of the present invention comprises a rotatable seal ring 
and a non-rotatable seal ring, each having a seal face in juxtaposed 
relation. Unlike other seal arrangements, the non-rotating seal ring is 
resiliently mounted from the impeller side of the pump housing such that 
it is urged into a sealing relation with the other seal ring in a manner 
assuring flexure of the non-rotating seal face despite pump operating 
conditions, i.e., despite the buildup of precipitate matter about the seal 
rings and associated mounting structure. By such construction, limited 
flexure of the non-rotating seal face is assured and the demanding 
manufacturing constraints are greatly lessened. 
The resilient mounting means for the non-rotatable seal ring includes seal 
carrier means operably associated with the pump housing. The mounting 
means provides for axial adjustment of the seal relative to the shaft 
whereby permitting proper seal face contact. As will be described in 
detail hereinafter, various forms or embodiments of resilient assemblies 
are radially disposed in a sealant manner between the seal carrier means 
and the non-rotatable seal ring. Such resilient assemblies include a 
spring biased member which is protected from the pump fluid and 
precipitate matter by a cover means. The spring biasing member provides 
the force necessary for urging and holding the end faces of the seal rings 
in pressure engagement. The protective cover means not only protects the 
biasing member from the often corrosive fluid product, but also, because 
of the internal flexibility between the cover and biasing member, imparts 
and assures a degree of flexibility therebetween whereby adding flexibilty 
to the non-rotating seal face despite the buildup of precipitate matter 
about the seal rings. 
In line with the above, a primary object of this invention is the provision 
of a seal assembly which is capable of maintaining a reliable seal between 
two relatively rotating members for long periods of time and under adverse 
conditions, as for example, the incursion of precipitate matter about the 
sealant rings. 
It is another object of this invention to provide a seal which has a high 
degree of resilient follow-up in the axial direction and which may 
tolerate considerable relative movement or runout between the members 
being sealed. 
It is still another object of this invention to provide a sealant assembly 
which is substantially self-aligning and whose construction permits a 
proper setting of the axial load on the seal faces without regard to the 
alignment of the pump housing with respect to the shaft. 
A further object of this invention is the provision of an improved face 
seal which eliminates the need for a coil spring biasing means. 
Still a further object of this invention is to provide a sealant assembly 
whose construction permits assembly and removal of the seal from the 
impeller side of the housing. 
Yet another object of this invention is to provide a readily replaceable 
face seal unit which is simple and practical in construction, efficient 
and reliable in performance, relatively inexpensive to manufacture and 
otherwise well adapted for the intended purposes.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
To simplify the invention disclosure, the drawings illustrate very little 
of the pump structure to which the invention is applied. FIG. 1 
illustrates a typical pump assembly 10 incorporating one embidoment of a 
mechanical seal assembly 12. Only so much of the pump assembly 10 is shown 
as necessary for an understanding of the present invention. Suffice it to 
say, the pump assembly 10 includes an impeller 14 adapted to forcibly move 
pump product including precipitate matter under pressure and in the usual 
manner. To effect this end, the impeller is connected to a rottatable 
shaft 16 which, in turn, is connected to a prime mover such as an electric 
motor (not shown). The impeller 14 is located in a housing 18 which may be 
bolted or otherwise affixed to a frame member 20. The housing 18 is 
provided with a fluid inlet port 22 and a fluid outlet port 24. The frame 
member 20 provides support which allows the shaft 16 to rotate and frame 
member 20 may be bolted or otherwise secured to a fixedly positioned 
support member 26. 
The mechanical seal assembly of this invention is constructed and arranged 
to substantially retard passage of fluid and precipitate matter being 
pumped from the impeller and pump housing along the motor shaft and 
ultimately to the motor or atmosphere. That is, the seal arrangement of 
the present invention provides an essentially fluid tight dynamic seal 
which retards the passage of pump product and precipitate matter between a 
first pressurized zone or area 30 wherein fluid and precipitate matter are 
being pumped along a predetermined path and a second zone or area 32 
extending along the drive shaft 16 to the motor. It must be appreciated 
that though the sealant means of this invention may be considered to be 
essentially fluid tight, some leakage across the seal does, of necessity, 
occur. This is true of all face type mechanical seals and is essential to 
the prolonged service life of the seal structure. 
The mechanical seal assembly 12 includes a pair of seal rings 36 and 38 
surrounding a shaft 16. In this first embodiment, best depicted in FIGS. 2 
and 5, the seal rings 36 and 38 are preferably constructed of a preformed 
sintered ceramic material, i.e., silicon carbide or other suitable wearing 
material depending on the particular environment in which the pump finds 
utility. Each seal ring has an opposing lapped seal end face 40 and 42. 
The abutment of end surface 40 with surface 42 provides the dynamic seal 
therebetween. The seal ring 36 rotates with the shaft 16 through its 
connection with a cylindrical sleeve 44, the latter being operatively 
associated with the shaft 16 and abutting the impeller 14. In comparison, 
the other seal ring 38 is relatively stationary and is resiliently mounted 
such that its seal face 42 is permitted to flex during pump operation. 
Unlike other seal arrangements, and for purposes of convenience, the 
mechanical seal of the present invention is mounted from the impeller side 
of the pump housing. By this construction, the drive assembly and 
alignment of the coupling between the drive motor and pump shaft is not 
disturbed. The seal ring 38 is operatively connected to a seal carrier 
means 46. In this embodiment, the seal carrier means includes a generally 
cylindrical bracket 48. As best illustrated in FIG. 3, at one end, the 
bracket 48 is provided with at least two projections 50 and 52 extending 
axially therefrom. Each of these projections is provided with a threaded 
aperture 54 which receives a fastener means 56 which extends outwardly 
from the bracket projections and is secured to the pump housing preventing 
rotation of the cylindrical bracket 48 and thereby the seal ring 38. 
Turning to FIGS. 4 and 5, in the preferred embodiment, C bolts are used as 
the fastener means 56 for securing the bracket 48 and thereby the 
mechanical seal assembly against rotation relative to the housing. The 
free end of each fastener 56 is slideably arranged in association with a 
threaded member 58 projecting from a wall 60 of the housing 18. To axially 
position the seal carrier means 46 and thereby the seal ring 38 within the 
housing, operator accessible adjustable members 62 and 64, carried on the 
threaded members 58, and arranged on opposite sides of the C bolts serve 
to lock the seal carrier means 46 in any desired axially adjustable 
position. If desired, the axial disposition of the seal carrier means and 
thereby the seal ring 38 may be adjusted while the pump is operating 
through axial movement of members 62 and 64. 
Turning now to FIG. 5, at its other end, the cylindrical bracket 48 is 
provided, in the first embodiment, with an annular concave groove 66. The 
sintered seal ring 38 is provided with a substantially similar annular 
groove 68. The two grooves 66 and 68 are so orientated to face one 
another. Radially interposed, in a sealant manner, between the two concave 
grooves is a circular elastomeric assembly 70. The assembly 70 comprises a 
disk like ring or diaphragm 74 generally in the form of a cone frustum 
which is preferably formed of a spring steel and which is encapsulated in 
an elastomeric material 75. The disk like ring 74 may include a single 
diaphragm member or a plurality of members having slotted overlying or 
corrugated fingers for effecting the same results. It should be noted that 
the grooves 66 and 68 on the bracket 48 and seal ring 38, respectively, 
are sized such that when the elastomeric assembly 70 is positioned 
therebetween, the elastomeric assembly is placed in compression sufficient 
to maintain a sealant and driving relationship therebetween. 
By this construction, the elastomeric nature of the assembly along with its 
geometric configuration serves to act as a Belleville spring against the 
ring 38 whereby keeping the sealant face 42 in contact with seal face 40 
of the rotatable seal ring 36. Moreover, it is important to note that the 
seal ring 38 is hydraulically balanced. That is, and as apparent from FIG. 
5, the end seal face 42 of ring 38, albeit axially spaced from, is 
radially disposed near the midpoint of the diaphragm or ring 74, thus 
providing hydraulic balance thereto. Additionally, the concave groove 66 
in the cylindrical bracket 48 may be cut, i.e., formed, with a projecting 
lip 76 so that the seal ring 70 tends to snap or detent into position 
thereby facilitating assembly of the seal. Furthermore, the elastomeric 
material 75 surrounding the spring 74 permits a degree of internal 
movement or radial mobility therebetween which translates to the seal face 
42 despite the buildup of precipitate matter or other pump operating 
conditions about the seal rings 36 and 38. 
A modified form of the invention is illustrated in FIGS. 6 through 10. It 
is to be understood, however, that the second embodiment of the invention 
has a similar purpose to that of the first embodiment and may be likewise 
arranged in a pump housing or assembly 110. But, for purposes of 
simplicity, only those components necessary for an understanding of the 
invention will be described. The mechanical seal assembly 112 includes a 
pair of seal rings 136 and 138 surrounding the driven pump shaft 116. The 
rotatable seal ring 138 and non-rotating seal ring 136, each have a seal 
face 140 and 142, respectively, which are arranged in opposed relation 
with their seal faces being resiliently urged toward one another in a 
manner hereinafter described. Seal rings 136 and 138, in the preferred 
embodiment, are the mirror image of one another, and are preferably 
constructed of a ceramic material such as silicon carbide. The seal ring 
138 may be bonded or otherwise secured for rotation with the sleeve 144 
carried by the pump shaft 116. The other seal ring 136 is bonded or 
otherwise secured to a cylindrically stepped ring member 143. Adjustable 
seal carrier means 146 including bracket means 148 are provided for 
mounting the seal ring 136 relatively stationary or against rotation with 
respect to the pump housing 110. The method and means for mounting the 
seal carrier means 146 and its cylindrical bracket means 148 to the pump 
housing are substantially the same as in the first embodiment and, thus, 
no further discussion will be devoted thereto. 
At its other end, a resilient ring assembly 170 radially spans the 
distance, and is disposed in a sealant manner between the bracket means 
148 and the ring member 143. The resilient ring assembly 170 comprises an 
apertured frusto conically shaped metal diaphragm 172 of one or more plies 
which is positionally accommodated within suitable grooves 166 and 168 
provided on the bracket means 148 and annular ring member 143, 
respectively. As seen in FIGS. 8 and 9, the metal diaphragm 172 is 
provided with notches or teeth 182 on both the inner rim 184 and outer rim 
186 thereof. Turning to FIGS. 6 and 7, such notches 182 or teeth are 
adapted for engagement with corresponding detents 188 on the bracket 148 
and on the annular member 143 thus yielding greater torque transmission 
capability to this arrangement. A pair of elastomeric rings 190 and 192, 
disposed proximate the inner and outer rims of the diaphragm 172, protect 
or seal against the passage of pump fluid or other matter thereby. In the 
preferred embodiment, the elastomeric rings comprise a pair of Viton or 
silicone rubber "O" rings. A pair of retainer means 194 and 195 suitably 
accommodated in the bracket means 148 and the annular member 143 serve to 
releasably hold the diaphragm 172 and rings 190, 192 in assembled 
positional relation. 
In an environment where a corrosive matter may contact the diaphragm, an 
alternative to the elastomeric rings may be used. As shown in FIG. 10, a 
rubber cover 198 may be used to protect the diaphragm against corrosive 
matter. In FIG. 6, the cover is shown in dotted lines. With either 
embodiment, it will be appreciated that the thrust of the spring diaphragm 
172 acting on the annular member 143 will serve to urge the seal ring 136 
toward the seal ring 138 thus enhancing the dynamic seal between the seal 
faces 140 and 142. Moreover, the resilience of the diaphragm 172 along 
with the inherent mobility between the diaphragm and the rings 190 and 192 
will add to the flexure ability of the non-rotating seal ring face 142 
despite operating conditions within the pump assembly. 
Yet another embodiment of a mechanical seal assembly is schematically 
depicted in FIGS. 11 through 16. Although the purpose of all the 
embodiments is substantially the same, i.e., to provide a dynamic seal in 
a pump environment, this third embodiment has the capability of 
withstanding higher pressures within a pump housing 210 and, yet, provides 
the necessary flexure required for the non-rotating seal face despite pump 
operating conditions. The mechanical seal assembly 212 includes a pair of 
seal rings 236 and 238 surrounding the pump drive shaft 216. Both seal 
ring 236 and 238 have a seal face 240 and 242, respectively arranged in 
opposed relation with their seal faces being resiliently urged toward one 
another. Seal rings 236 and 238, in this embodiment, may be the mirror 
image of one another and are preferably constructed of a ceramic material 
such as silicon carbide or other suitable material depending on the pump 
environment. As in the other embodiments, the seal ring 236 is adapted for 
rotation with the pump drive shaft 216. The other seal ring 238 is 
preferably mounted in a non-rotatable fashion. The seal ring 238 may be 
bonded or otherwise secured to a cylindrically stepped ring member 243. 
Axially adjustable seal carrier means 246 is provided for mounting the 
non-rotary seal ring 238 from the impeller side of the pump housing. The 
mounting or carrier means 246 includes a tubular member or bracket means 
248 which is telescopically arranged over the pump drive shaft 216. 
Secured to one end of the tubular member 248 is a mounting assembly 250. 
In this embodiment, the mounting assembly 250 is comprised of a 
complementary pair of apertured C blocks 252 and 254. As best depicted in 
FIGS. 11, 12 and 13, the C blocks include an annular projection 256 
arranged for insertion into an annular groove 258 provided about the 
periphery of the tubular member 248. At the upper and lower extremes of 
each C block, there are provided flange portions 260 and 262. The upper 
and lower flange portion of each C block are releasably secured together 
by any suitable fastener means 264. The flange portions are provided or 
formed with complementary cutouts which, when assembled, define suitable 
openings or apertures 266. These openings or apertures 266 are suitably 
arranged and proportioned to accommodate threaded members 268 extending 
from a wall 261 of the pump impeller housing (not shown). To axially 
position the seal carrier means 246 and thereby the seal assembly 238 
within the pump housing, adjustable members or nuts 269 carried on the 
threaded members 268 and arranged on opposite sides of the flange portions 
260 and 262 serve to lock the seal carrier means 246 and thus the seal 
ring 238 in any desirable adjustable position. If desired, the axial 
disposition of the seal carrier means 246 and thereby the seal assembly 
238 may be adjusted, while the pump operates, through axial movement of 
members 269. 
At its other end, the tubular member 248 is provided with an elastomeric 
ring assembly 270 which is radially disposed in a sealant manner between 
the tubular member 248 and the ring member 243 of the seal ring 238. As 
schematically depicted in FIG. 11, the elastomeric ring assembly 270 of 
this third embodiment includes an annular array of plate segments 274, a 
protective fabric cover 276 arranged on one side or face of the plate 
segments 274, and a flexible diaphragm 278 arranged on the opposite side 
or face of the plate segments 274. As best illustrated in FIGS. 11 and 15, 
the plate segments 274 engage and are dispersed between detents or drive 
projections 280 provided both on the tubular member 248 and the annular 
member 243. Such a design increases the torque transmission capabilities 
of this sealant assembly. The plate segments 274 also allow this seal 
embodiment to withstand heavy pressure buildup within the pump housing. 
The protective fabric cover 276 disposed on one side of the plate segments 
274 is impregnated with a conical or spiral spring 282. The spiral spring 
282 in combination with segments 274 provides a low spring rate plus 
pressure capability. The protective cover 276 is held in place by inner 
and outer retainer rings 284 and 286 which are carried by the tubular 
member 248 and the annular member 243, respectively. On the side of the 
plate segments 274 opposite the protective cover, both the tubular member 
248 and the annular member 243 are provided with a projecting lip 288. 
Interposed between the lip 288 and the plate segments 274 is flexible 
diaphragm 278 which has a portion or section which bellows outwardly from 
the plate segments 274 leaving a void or gap 292 therebetween. Into this 
void or gap there may be injected a gel like substance. The gel like 
substance may be of varying forms but should be one that does not change 
substantially in temperature and which is compatible with the rubber O 
rings and covers used in this construction. The flexible diaphragm 278 
both resists the incursion of solids against the flexible plate like 
segment and maintains an adequate range of movement of the seal face 242 
despite the accumulation and even hardening of precipitates thereabout. 
The insertion of a gel like substance into the void or gap 292 between the 
flexible diaphragm 278 and the plate like segments 274 also provides a 
degree of flexure for diaphragm movement despite the precipitate buildup 
and other pump operating conditions. 
From the above description, it is apparent that in each of the foregoing 
embodiments an improved form of face type mechanical seal has been 
provided. In each embodiment, the stationary seal is mounted to the pump 
housing from the impeller side of the housing in such a manner that a 
degree of flexure for the non-rotating seal face is provided despite pump 
operating conditions. That is, despite the buildup of precipitate matter 
about the seal rings and the supporting means therefor, inherent in each 
of the designs illustrated and described is the ability of each to support 
and permit flexure of the non-rotating seal face while concurrently 
providing a thrusting force between the seal rings. This thrusting force 
enhances the sealing effect between the seal faces to accomplish the ends 
and objectives mentioned above. 
Thus, there has been provided an improved mechanical seal for pumps which 
fully satisfies the objects, aims and advantages setforth above. While the 
invention has been described in conjunction with specific embodiments 
thereof, it is evident that may alternatives, modifications and variations 
will be apparent to those skilled in the art in light of the foregoing 
description. Accordingly, it is intended to embrace all such alternatives, 
modifications, and variations as fall within the spirit and broad scope of 
the appended claims.