AU427998B2 - Sanitary seal - Google Patents

Description

3'3 5 8 3 7. FIELD OF THE INVENTION This invention relates to an improved seal assembly and,

in particular, relates to a cartridge-type seal assembly

which can be easily disassembled for cleaning, and which

is designed to minimize collection or entrapment of contam- inating materials or bacteria, either between the seal faces or elsewhere.. BACKGROUND OF THE INVENTION Seal assemblies utilized on food processing equipment and the like generally require that the equipment be period- ically shut down to enable the parts thereof, including the seal assemblies, to "be disassembled and cleaned so as to remove any collected material or bacteria which may be trapped therewithin. Thus, insofar as the seal is concerned, there has long existed a need for a sanitary-type seal assembly which can be successfully operated for substantially long periods of time without collecting contaminating materials or bacteria. Further, there has long existed a need for a sanitary seal assembly which, when the machine is shut down for cleaning purposes, can be easily and quickly disassembled, cleaned, .and reassembled so as to minimize both the maintenance involved and the machine shut down time. While various types of seal assemblies have been designed for use as sanitary seals, none of these prior seal construc- tions have, to the best of.my knowledge, overcome the two" primary problems referred to above, which two primary prob-

lems may be restated as the provision of a seal assembly which is designed to minimize the collection or retention of material or bacteria which can cause bacterial growth or

contamination, and the provision of a seal assembly which can be easily and quickly disassembled, cleaned and reassembled so as to substantially minimize maintenance and equipment shut

down time. 427998

3 3,58 3 171, Accordingly, it is an object of the present invention

to provide an improved seal assembly, particularly a sanitary seal, which overcomes the disadvantages of the prior known seal assemblies and is able to successfully overcome or at least minimize the two above-mentioned problems. Specifically,

it is an object of the present invention to provide: 1. An improved sanitary seal assembly which can be easily disassembled, cleaned and reassembled. 2. An improved seal assembly, as aforesaid, which is of the cartridge-type so as to enable the seal to be disassembled and reassembled substantially as a unit. 3. An improved seal assembly, as aforesaid, which sub- stantially eliminates sharp corners and/or recesses wherein material and/or bacteria can collect, whereby the seal is thus substantially self-cleaning. 4. An improved seal assembly, as aforesaid, which can be operated for longer periods of 'time without requiring shut down of the equipment with which it is associated for cleaning purposes. An improved seal assembly, as aforesaid, on which some cleaning operations, at least between the sealing faces, can be carried out during operations.- An improved seal assembly, as aforesaid, which can be easily and economically manufactured, which is dependable and Sefficient in operation, and which meets normal sanitary re- quirements. Other objects and purposes of the invention will be appar- ent to persons acquainted with devices of this general type Supon reading the following specification and inspecting the accompanying drawings.

BRIEF DRAWINGS view of the improved sani- Figure 1 is a central sectional to the present invention. tary seal construction according view taken along the Figure 2 is a fragmentary sectional line i-Il of Figure 1. view taken along the Figure 3 is a fragmentary sectional line III-III of Figure 1. view taken along the Figure 4 is a fragmentary sectional line IV-IV of Figure 1. used in the following descrip- Certain terminology will be only and will not be limiting. tion for convenience in reference "leftwardly" and "right- The words "upiardly"i "downwardly", in the drawings to which wardly" will refer to directions "inwardly" and "outwaral.y" wiL.. reference is made. The words the and away from, respectively, refer to directions toward and designated parts thereof. geometric center of the device refer to the direction The word "inwardly" will specifically being the rightward direc- toward the inside of the housing, will refer to the direc- tion in Figure 1, where "outwardly" being the leftward direction tion exteriorly of the housing, will include the words above in Figure. 1. Said terminology thereof and words of specifically mentioned, derivatives similar import. SUMMARY OF THE INVENTION the present invention are met The objects and purposes of which is dosposed between by providing the seal construction housing, the shaft ex- a rotatable shaft and a surrounding housing housing through a zemovable tending outwardly from the includes an insert or station- portion. The seal construction and the removable housing portion ary seal member mounted on

3 8,583i7. encircling the shaft, the insert being keyed to the housing by means of a pin-and-groove connection. The groove is formed in the insert and is provided with a smoothly curved surface.. The insert has a seal face which seals against a further seal face provided on a rotatable seal unit which comprises a rotateable seal ring which also encircles the shaft, same being mounted for floating movement relative to the shaft. The rotatable seal ring is interconnected, as by a plurality of drive pins, to a collar which is fixedly secured to the shaft by means of a pin-and-slot connection, the slot again being defined by a smooth or continuous surface free of'sharp edges or corners. The drive pins, which axially secure the rotat- able seal ring to the collar, extend through grooves in the collar and have enlarged head portidns for preventing axial separation of the seal ring and the collar. A resilient spring is confined between the rotatable seal ring and the collar for urging the rotatable seal ring into sealing engagement with

the i.nsert. The seal construction can be cleaned by removing the removable housing portion, whereupon the insert can like- wise be removed from the shaft, with the rotatable seal unit then also.being removed as a unit. The overall seal construc- tion can easily be reassembled on the shaft in the reverse manner. Cleansing of the seal construction is further assisted by means of a cleaning fluid, particularly steam, which dur- iing manual operation of the seal may be supplied to a closed chamiber defined between the external surface of the shaft .and the internal peripheries of the insert and rotatable seal

ring, whereupon the steam then flows radially outwardly between the abutting seal faces for both cleaning, cooling and lubrica- ting same.

3'3,58 3/71 DETAILED DESCRIPTION Figure 1 illustrates therein an improved sanitary seal assembly 11 constructed according to the present invention, which seal assembly 11 is disposed for sealingly coacting be- tween a rotatable shaft 12 and a surrounding housing 13. The housing 13 includes a removable cover plate 14 which is secureC to the housing in any suitable manner, such as-by screws 16. The cover plate 14 has an opening 17 through which extends the rotatable shaft 12. The seal assembly 11 includes an insert or stationary seal ring 21 having a sleeve portion 22 disposed within the housing opening 17 and encircling the shaft 12. The seal

ring 21 includes an annular flange 23 disposed adjacent and in abutting engagement with the inner surface of the cover plate 14. The flange 23 is provided with an axial slot 24 extending therethrough, the bottom surface 26 of which is

rounded so that the slot is free of sharp edges or corners. A pin 27 is fixedly secured to the cover plate 14 and extends rearwardly into the slot 24 for nonrotatably relating the insert 21 to the cover plate 14. Other construction details

of the insert 21 will be described hereinafter. The insert 21, which is preferably constructed of carbon, is provided with a transverse annular seal face 28 on the inne axial end thereof, which seal face 28 is adapted to be main- tained in abutting sealing engagement with a further trans- verse annular seal face 29 as provided on the adjacent axial end of a rotatable seal ring 31. The rotatable seal ring 31 includes a base wall portion 32 having an opening.33 therethrough, in which is positioned the rotatable shaft 12, the opening 33 being larger than the

shaft 12 so as t, enable the seal ring 31 to angularly float

427 9-98

33,583/71 relative to the shaft 12 in a conventional manner so as to maintain the seal face 29 in firm abutting engagement with the seal face 28. The seal ring 31 also includes an annular flange 34 which extends axially inwardly from the base wall portion 32, the annular flange 34 encircling, and spaced radially outwardly from; the shaft 12. The flange 34 has an inner annular wall 36 which is spaced from the external surface of the shaft 12 so as to define an annular recess 37 there- between. A conventional compression spring is disposed within the annular recess 37 in surrounding relationship to the shaft 12, the one end (leftward end in Figure 1) of the spring 38 being disposed in abutting engagement with a conventional elastoreric seal ring 39, preferably an O-ring'. The seal ring 39 is dis-

posed so as to sealingly abut the rear face 41 of the base wall portion 32 and, when deformed, will also sealingly engage the external periphery of the shaft i2. The rear wall 41 and the inner annular wall 36 are joined by a rounded corner surface 42, which surface 42 is preferably formed with a radius sub- stantially equal to the radius of the O-ring 39.so that the O-ring will thus resiliently and snugly seat against the corner surface 42. The other end (rightward end in Figure 1) of the spring 38 is disposed in abutting engagement with the front face of an annular collar 44, whereupon the spring thus urges the' collar 44 rearwardly into abutting engagement with a shoulder 46 formed on the shaft 12. The collar 44 is provided with an

internal slot 47 extending axially thereof, which slot is also ,provided with a rounded surface 49 on the bottom thereof so that the slot is thus free of sharp edges or corners. A pin

3 ,5 8 3/71 48 is fixedly secured to the shaft 12 and extends radially

outwardly therefrom into the slot 47 so as to nonrotatably

connect the collar 44 to the shaft 12. While the collar 44 is nonrotatable relative to the shaft 12, nevertheless the internal diameter of the collar is slightly greater than the

external diameter of the shaft so as to enable the collar to

be freely axially removed or mounted on the shaft, whereby

the spring thus resiliently urges the collar against the

shoulder 46.

The collar 44 is nonrotatably connected to the rotatable seal ring 31 by means of one or more axially extending drive

pins 51, which pins 51 are fixedly secured to the seal ring

31 and extend axially rearwardly so as to engage the flange

portion 52 of the collar 44. The flange portion 52 of the collar 44 is provided with one or more locking recesses 54

therein. The recess 54 accommodates therein the main body of the pin 51 with the enlarged head 56 of the pin being dis-

posed on the rearward side of the flange as illustrated in

Figure 1.

The locking recess 54, as illustrated in Figure 2, specif-

ically includes a radial slot portion 57 which has a width

slightly greater than the diameter of the head 56 so as to

enable the head to freely pass axially therethrough. The radial slot portion 57 is also provided with a rounded surface

58 on the bottom thereof so that the slot 57 is free of sharp

edges or corners. The locking recess 54 also includes a trans- verse slot 59 which extends circumferentially or laterally

relative to the radial slot 57. The transverse slot 59 has a width slightly greater than the diameter of the pin 51 so

as to accommodate the main pin body therein, while at the same

33,583/171 time the width of the slot 59 is less than the diameter of the head 56 so as to prevent axial separation between the collar 44 and the rotatable seal ring 31 when the pin is disposed within the transverse slot 59. The seal assembly 11 also preferably includes means for continuously cleaning the seal faces 28 and 29 during opera- tion of the seal assembly. Particularly, there is provided a source 61 of cleaning fluid, preferably steam. The source

61 is connected by means of intermediate conduits 62 to a pair of diametrically opposite ports 63 which are formed in the cover plate 14. The ports 63 in turn communicate with a pair of radial passageways 64 which extend through the stationary seal ring 21 and communicate with an annular chamber 66 which is defined between the outer surface of the shaft 12 and the inner peripheries of the seal rings 21 and 31. The chamber 66 is in part defined by means of an annular groove 67 formed in the periphery of the shaft 12 adjacent the ports 64. The chamber 66 additionally includes an annular clearance space 68 defined between the shaft 12 and station- ary seal ring 21 and a further annular clearance space 69 as defined between the shaft 12 and the rotatable seal ring 31. The one end of the annular chamber 66 is closed by means of the the resilient O-ring 39, whereas the other axial end of chamber 66 is closed by means of a further resilient elasto- meric seal ring 71 which is positioned within a groove 7Z2 formed within the periphery of the shaft 12 and is disposed in rotatable sealing engagement with the inner periphery of the stationary seal ring 21. The resilient ring 71 is, as illustrated in Figure 1, positioned closely adjacent, but axially outwardly from, the inner ends of the radial ports 64.

3 0,58371 There is additionally provided a further pair of resilien

elastomeric seal rings 73 and 74, which seal rings are dispose,

in grooves formed on the external periphery of the stationary

seal ring 21 and sealingly engage the wall 17. The seal rings 73 and 74 are disposed on opposite axial sides of the ports 63

and 64 so as to prevent the escape of the steam supplied to

the chamber 66.

ASSEMBLY AND OPERATION

The operation of:the seal assembly .11 will be briefly, de-

scribed to insure a complete understanding thereof.

When the shaft 12 is rotating relative to the housing 13,

the rotation of the shaft causes a corresponding rotation of

the collar 44 and the rotatable seal ring 31, Since spring 38 resiliently urges the rotatable seal ring 31 axially toward

the stationary seal ring 21, the seal face 29 is resiliently

urged into rotatable sliding bearing engagement with the seal face 28. Due'to the permissible floating movement of the seal

ring 31, it will remain in flush bearing engagement with the

seal ring 21 irrespective of slight misalignment or irregular-

ities between the shaft 12 and the housing 13, Any tendency for fluid, to escape from the housing is substantially prevented

by the seal assembly 11 due to the sealing engagement created by the resilient seal rings 73, 74 and 39, and additionally

due to the sealing engagement between the seal faces 28 and 29.

To assist in maintaining the seal faces 28 and 29 in'a

clean or sanitary condition a cleaning fluid, such as steam,

is preferably supplied from the source 61 through conduits

62 into the ports 63, whereupon the fluid flows through passage

64 into the annular chamber 66 and thence radially outwardly between the seal faces 28 and 29. The radial outward flow of

3 8 3 71 28 and 29 thus ant the cleaning fluid between the seal faces 28 and 29 thus maintain the seal faces in a clean and'sanitary condition. The flow of cleaning fluid between the seal faces 28 and 29 also assists tem- in maintaining the seal faces at a substantially uniform perature and additionally functions as a lubricant for the seal faces. During operation of the seal assembly, there is little seal as- tendency for material or bacteria to collect on the and 54 are sembly since all of the grooves or recesses 24, 47 are free provided with smooth and continuous surfaces which of sharp or dead corners. This configuration makes it diffi- is cult for material to collect and thus the seal assembly a clean partially self-cleaning and, accordingly, remains in of and sanitary condition for a substantially longer period time than conventional seal assemblies. for When it is desired to remove the seal assembly 11 from cleaning purposes, the cover plate 14 is first removed 21 can then the.housing 13, whereupon the stationary seal ring (left- be removed from the shaft 12 or at least moved axially wardly in Figure 1) away from the housing 13. The seal ring 21 is thus more accessible for cleaning purposes. or. After the stationary seal ring 21 has been removed rotating displaced axially leftwardly on the shaft 12, the leftwardly seal ring can also be removed or displaced axially since the on the shaft for cleaning purposes. Particularly, interconnected rotating seal ring 31 and collar 44 are axially can be com- by means of the drive pins 51, this subassembly inasmuch as pletely removed or displaced axially as a unit axial sep- the heads 56 of the drive pins 51 prevent complete collar 44 when aration of the rotating seal ring 31 from the 427998

3'3,58 3/71 in the position illustrated in Figure 2. Thus, this subassem- bly can be removed as a unit into a more accessible position,

whereupon the rotating seal ring 31 can then be angularly

displaced relative to the collar 44 until the drive pins 51

are moved from the transverse slots 59 into the radial slots

57, the heads 56 thus passing freely through the radial slots

57 to permit complete axial separation of the seal ring 31

and the collar 44. This thus permits all of the individual members to be completely cleaned.

After all of the individual components of the seal assem-

bly have been cleaned, then the seal assembly is reassembled in the reverse manner as explained above.

While the rotating seal ring 31 and the collar 44 can be

assembled or disassembled as a unit as explained above, it is

also possible that these members could be individually assem-

bled or disassembled. For example, during disassembly, the

rotating seal ring 31 can, if desired, be initially angularly

displaced so as to move drive pin 51 into radial slot 57,

whereupon the rotating seal ring 31 would be individually re-

movable from the shaft 12, with the collar 44 likewise being

individually axially removable from the shaft. The manner in

which the drive pins 51 and the locking recesses 54 cooperate

thus permit the rotating seal ring 31 and the collar 44.to be

assembled or disassembled either as a unit or individually,

depending upon whatever is most convenient under the specific

operating conditions encountered.

Although a particular preferred embodiment of the inven-

tion has been disclosed in detail for illustrative purposes,

it will be recognized that variations or modifications of the.

disclosed apparatus, including the rearrangement of parts,

lie within the scope of the present invention.

427998

3 3,58371 ARE AS FOLLOWS:- THE CLAIMS DEFINING THE INVENTION

-1-

A mechanical seal construction for use between a wall"

and a shaft rotatable relative to said wall and extending

through an opening therein, said seal construction comprising:

first seal means including a first annular seal member

fixable-with respect to said wall, said first seal member

including a sleeve portion sealingly disposed within said

opening in surrounding relationship to said shaft and having a first annular seal face thereon substantially transverse to

the axis of said shaft; second seal means affixable to said shaft for rotation

therewith, said second seal means including a second annular

seal member disposed in surrounding relationship to said

shaft and mounted for at least limited floating movement

relative to said shaft, said second seal member having a

second annular seal face thereon substantially transverse di- to the axis of said shaft and disposed adjacent to and

rectly opposite said first seal face; said. second seal means further including an annular

collar nonrotatably affixable to said second shaft;

said second seal means also including coupling means

coacting between said second seal member and said collar

for transmitting torque from said collar to said re- second seal member for rotating same with said shaft in

sponse to rotation in one direction, for normally preventing said collar and said second

seal member from being axially disconnected while permitting

limited relative axial movement therebetween, and

1R 427998

Claims (1)

1. 8 1'71 3 3,colar for permitting sai' c and said second seal

   member to be axially disconnected in response to relative

   rotation therebetween in the opposite direction;

   said second seal means still further including spring

   means disposed between said second seal member and said collar

   in surrounding relationship to said shaft for normally resili-

   ently urging said second seal face into rotatable sliding

   sealing contact with said first seal face; and

   means for cleaning said first and second seal faces when

   disposed in rotatable sliding sealing contact with one another,

   said cleaning means including a closed annular chamber between

   said shaft and said first and second seal members, said chamber

   communicating with the inner edges of said seal faces, and

   means for supplying cleaning fluid to said chamber, whereby

   said cleaning fluid will flow radially outwardly between said

   first and second seal faces for cleaning same. -2-

   A seal construction according to Claim 1, in which said

   coupling means includes a drive pin extending axially between

   said collar and said second seal member, said drive pin having

   one end thereof fixedly secured to one of said collar and said

   second seal member, the other end of said drive pin being

   slidably received within and extending through a recess formed

   within the other of said collar and said second seal member,

   the other end of said drive pin having a radially enlarged

   head portion fixedly secured thereto, and said recess including

   a first slot portion having a width large enough to axially

   accommodate therein the head portion of said drive pin, and

   said recess further including a second slot portion communica-

   ting with said first slot portion and having a width large

   IA 427998

   3 3,583/71 enough to slidably accommodate therein the main body portion of said drive pin but smaller than said head portion, whereby

   said collar and said second seal member are axially connected

   together by said drive pin when same is disposed in said

   second slot portion while said drive pin still permits limited

   relative axial movement therebetween.

   -3-

   A seal construction according to Claim 2, in which said first slot portion opens in a radial direction, and said

   second slot portion extending transversely of said radial

   direction.

   -4-

   A seal construction according to Claim 2, in which the one end of'said drive pin is fixedly connected to said second

   seal member, and wherein said recess is formed within said

   collar, and the head portion of said pin is disposed adjacent

   the axial side of said collar opposite from said second seal

   member, said second seal member and said collar being axially

   disconnected by relative rotation therebetween so as to angularly

   displace said drive pin into said first slot portion for en-

   abling said head portion to freely axially move through said

   first slot portion.

   A seal construction according to Claim 2, in which a pin-

   and-slot connection is provided between said collar and said. shaft for nonrotatably affixing said collar to said shaft,

   said pin-and-slot connection including a pin fixedly secured to said shaft and extending radially beyond the periphery

   thereof, and a slot extending axially of said collar and ex-

   tending inwardly from the inner radial periphery thereof,

   :1 .427998

   3 3,58 371 the pin on said shaft extending into the slot in said collar for nonrotatably relating.said collar to said shaft, said slot on said collar being provided with a smooth surface free of sharp edges or corners for preventing collection of bacteria or the like, and the slot'portions of said recess also being formed with smooth surfaces which are free of sharp edges or corners so as to also prevent the collection of bacteria or the like. -6-

   A seal construction according to Claim 5, wherein said -ehousig includes a removable 4husin4 cover having said open- ing therein, and a second pin-and-slot connection coacting between said removable cover and said first seal member for nonrotatably interconnecting same, said second pin-and-slot connection including a second pin fixedly secured to and ex- tending inwardly from said cover and a second slot extending axially through a portion of said first seal member adjacent the outer periphery thereof with said second pin extending into said second slot, said second slot being formed with a smooth surface free of sharp edges or corners for preventing the collection therein of bacteria or the like. -7-

   A seal construction according to Claim 1, wherein said cleaning means includes a port formed in said hea4ig with the outer end of said port being connected to a source of:

   pressurized cleaning fluid, the inner end of said port ter-

   minating adjacent said first seal member, and said first seal

   member including a passage extending radially therethrough

   with the outer end of said passage communicating with the

   inner end of said port and the inner end of said passage

   A 427998

   3 3,58 3/71 communicating with annular chamber, a first resilient elasto- merib seal ring disposed between and sealingly engaging said first seal member and said shaft for sealingly closing one axial end of said annular chamber, and a second resilient elastomeric seal ring disposed between and sealingly engaging said second seal member and said shaft for sealingly closing the other axial end of said annular chamber. -8-

   A seal construction according to Claim 7, wherein said spring means includes a compression spring having one end thereof coacting with said second elastomeric seal ring for resiliently urging said second seal ring into sealingly en- gagement with a rounded shoulder formed on said second seal member. -9- A seal construction according to Claim 8, in which said coupling means 'includes an axially extending drive pin ex- tending between said collar and said second seal member, said drive pin having one end thereof fixedly secured to one of said collar and said second seal member, the other end of said drive pin being slidably received within and extending through a recess formed within the other of said collar and said second seal member, the other end of said drive pin hav- ing.a radially enlarged head portion fixedly secured thereto, and said recess including a radially directed slot portioi having a width large enough to axially accommodate therein the head portion of said drive pin, and said recess further including a transversely extending slot portion communicating with said radially directed slot portion and having a width large enough to slidably accommodate therein the main body i portion of said drive pin 3 3583 171 butsmaller than said head portion, whereby said collar and said second seal member are axially connected together by said drive pin when same is disposed in said transverse slot portion while said drive pin still permits limited relative axial movement therebetween.

   A seal construction according to Claim wherein said one end of said drive pin is fixedly connected to said second seal member, wherein said recess is formed within said collar, the head portion of said pin being disposed adjacent the axial side of said collar opposite from said second seal member, said second seal member and said collar being axially dis- connected by relative rotation therebetween so as to angularly displace said drive pin into said radially directed slot por- tion for enabling said head portion to freely axially move through said radial slot portion, wherein a first pin-and-slot connection is provided between said collar and said shaft for nonrotatably affixing said collar to said shaft, said first pin-and-slot connection including a first pin fixedly secured to said shaft and extending radially beyond the periphery thereof, .and a first slot extending axially of said collar and extending inwardly from the inner radial periphery thereof, said first pin extending into said first slot for nonrotatably affixing said collar to said shaft, wherein said ai in- cludes a removable 4heeeig-cover having said opening therein, and a second pin-and-slot conneption coacting between said removable cover and said first seal member for nonrotatably interconnecting same, said second pin-and-slot connection in- cluding a second pin fixedly secured to and extending inwardly from said cover, and a second slot extending axially through

   18 427.998

   33, 583/71 a portion of said first seal member adjacent the outer per- iphery thereof with said second pin extending into said second slot, said first and second slots and said recess being formed with smooth surfaces free of sharp edges or corners for preventing the collection therein of bacteria or the like.

   Dated this 15th day of September, 1971

   DURAMETALLIC CORPORATION

   By its Patent Attorneys

   DAVIES COLLISON

   3 3158371