Mechanical seal

An improved mechanical seal of the type useful to form a seal between a stationary housing and a rotatable shaft. The seal comprises a rotatable seal element and a stationary seal element. There is an elastic element which forces the rotatable and stationary seal elements to sealingly engage. The mechanical seal can comprise removable clips to connect the seal to the housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to mechanical seals, and more particularly 
having an improved mechanical seal having an elastic element and a 
mechanical seal having an improved means to secure the seal to a machine 
stationary housing. 
2. Description of the Related Art 
A mechanical seal provides a seal between a rotatable element, typically a 
shaft, and a stationary housing of an apparatus, typically containing 
fluid. Such seals are often associated with a fluid pump having a shaft 
extending through a pump housing wall. The pump shaft can be coupled to a 
motor through a motor shaft. The mechanical seal forms a seal between the 
pump shaft and the outer surface of the pump housing. Mechanical seals for 
such applications are commercially available and are described in U.S. 
Pat. Nos. 4,639,000; 4,832,351, 4,989,882; and 4,993,720. Such seals 
endure rigorous environments and last for extended time periods. 
Seals which are known in the art comprise rotatable components and 
stationary components which contact to form a seal at opposing sealing 
surfaces. The rotatable components include a shaft attachment means. Such 
a means is typically a sleeve having an inner perimeter surface which 
sealingly fits over the outer perimeter surface of the shaft and is 
connected to the shaft by connecting means such as set screws. An "O" ring 
typically provides a seal between the shaft and the sleeve. There is a 
rotatable circumferential seal element interconnected to the sleeve so as 
to rotate when the shaft and sleeve rotate. The sleeve extends axially 
along the shaft. 
The stationary components comprise a gland which extends circumferentially 
around the shaft. The gland abuts against the outer housing surface around 
the shaft. There is typically a sealing gasket interconnected to the gland 
and located between the gland and the housing. The gland functions as a 
base by which the seal is attached to the housing. The connection is 
typically accomplished by bolts extending from the outer housing wall. The 
bolts pass through slots or connecting extensions extending radially from 
the gland through the connecting slots or connecting extensions and 
secured with nuts. A stationary seal element is located between the inner 
circumferential surface of the gland facing the shaft (i.e. the gland 
inner surface) and the shaft. The stationary seal is directly or 
indirectly connected to the stationary gland. There are suitable means 
such as described in U.S. Pat. Nos. 4,832,351 and 4,989,882 to axially 
center the various stationary elements on the shaft. A circumferential 
spacing is maintained between the stationary elements, and the shaft and 
various of the rotating elements. 
The stationary and rotatable components meet at opposing sealing surfaces 
of the rotatable and stationary seal elements. There is typically a metal 
spring which forces either one of the seal elements toward the opposing 
seal element to cause the opposing surfaces to be pressed together. The 
opposing seal element has restricted axial movement and the surface of one 
seal element is forced by the spring against the surface of the opposing 
seal element. Thereby, a seal is formed between the opposing sealing 
surfaces, i.e., the rotatable and stationary sealing elements. 
Mechanical seals known in the art have at least one "O" ring associated 
with the sealing element being acted on, by the spring. The spring forces 
this element toward the opposing element to form a seal. The "O" ring must 
form a seal not withstanding the axial movement and is known as a 
"dynamic" "O" ring. Additionally, the dynamic "O" ring is located in an 
"O" ring slot which can clog. The spring must therefore provide force to 
cause the sealing elements to come together under sufficient pressure to 
form a seal while overcoming the resistance of the dynamic "O" ring and 
clogging in the area of the dynamic "O" ring. It would be desirable to 
eliminate the dynamic "O" ring as well as the metal spring. 
Additionally, the means to connect the mechanical seal to the housing is 
integrated into the structure of the stationary components. The mechanical 
seal is often set in place and removed in the small space between the pump 
and motor. The means to attach the seal take up space and make access to 
the mechanical seal difficult for both installation and removal. A design 
with easier access to the seal elements at the location where the shaft 
extends from the housing is desireable. 
SUMMARY OF THE INVENTION 
The improved mechanical seal of the present invention includes an elastic 
spring element of the type useful to force a rotatable seal surface into 
sealing contact with a stationary seal surface. Additionally, the 
mechanical seal can be connected to a machine housing using removable 
clips to enable easier access for installation, maintenance and repairs to 
the mechanical seal and machinery to which it is attached, particularly in 
restricted spaces. 
The mechanical seal of the present invention is useful to form a seal 
between a stationary housing and a rotatable shaft having a shaft axis. 
The shaft has a shaft surface having a shaft perimeter and extends through 
an opening in the housing. The housing has an inner surface and an outer 
surface. 
The mechanical seal comprises rotatable components and stationary 
components. The rotatable components are interconnected to the shaft and 
rotate with the shaft. The stationary components are interconnected to the 
housing and do not rotate. The rotatable components and stationary 
components are positioned relative to each other so that a rotatable seal 
surface sealingly engages a stationary seal surface. Such a mechanical 
seal is particularly useful to form seals on machines which have rotatable 
shafts extending therefrom and fluid inside such as fluid pumps, i.e., 
water pumps. 
In a preferred embodiment the rotatable components comprises a sleeve 
having a shaft side inner wall. The inner wall has inner perimeter which 
fits over the outer perimeter of the shaft. A radial wall extends from the 
inner wall of the sleeve. A rotatable circumferential seal element is 
interconnected to the sleeve. The rotatable seal element has a rotatable 
seal surface. 
In a preferred embodiment the rotatable component further comprises a 
rotatable chamber defined by the shaft side inner wall, the radial wall 
and a circumferential outer wall. The outer wall extends from the radial 
wall over at least part of the shaft side inner wall and has openings. The 
rotatable circumferential seal element is located in the rotatable chamber 
with the rotatable seal surface facing the stationary seal surface. Where 
the chamber is in communication with the fluid in the housing, the fluid 
communicates into the rotatable chamber through the openings. 
A circumferential elastic element of the present invention is located 
around the sleeve between the radial sleeve wall and the rotatable seal 
element. The elastic element is an elastic, preferably elastomeric, 
sealing spring having an inner side adjacent to the sleeve inner wall, a 
radial wall side adjacent to the sleeve radial wall, a seal side adjacent 
to the rotatable seal element and disposed to engage and force the 
rotatable seal element axially away from the radial wall and toward the 
stationary seal element, and an outer side opposite the inner side. The 
outer side has an outer seal side surface extending for at least part of 
the circumference of the elastic element. The outer seal side surface 
extends angularly for at least part of the axial distance from the outer 
side surface at the seal side toward the inner side. 
Preferably, the outer side of the elastic element has an outer radial side 
surface extending for at least part of the circumferential element and 
extending angularly from the outer side at the radial side toward the 
inner side. Preferably, the elastic element outer seal side surface and 
outer radial side surface form a circumferential groove in the outer side. 
More preferably, the outer side grooves have cross-sectional shapes 
selected frown the group consisting of "U" and "V". 
It is preferred that the forces exerted by the elastic spring element at 
the radial wall side and at the seal side be relatively uniform across the 
respective surfaces. In order to compensate for the groove in the outer 
side surface there can be at least one and preferably two circumferential 
inner side grooves in the inner side of the elastic element. Preferably, 
the outer side groove and the inner side groove have a combined radial 
dimension at least equal to the radial length of the elastic element 
(distance from inner side to outer side). This enables the hydraulic 
forces to act in a balanced manner along the whole radial length of the 
elastic element. 
In certain embodiments addition elastic force can be provided by a spring 
means to force the outer seal surface toward the rotatable seal. The 
spring means can also force the outer radial surface toward the radial 
wall. The preferred springs are circumferential washer rings having a 
major plane at a greater angle to the radial plane of the elastic than the 
seal side surface and radial side surface. The washer is able to force the 
seal side of the elastic element toward the adjacent seal element. 
The stationary components comprise a gland extending around the perimeter 
of the shaft. The gland has a gland component which can sealingly abut 
against the housing around the shaft. A stationary circumferential seal 
element is interconnected to the gland. The stationary seal element has a 
stationary seal surface. The gland is located on the shaft at a position 
whereby the stationary seal surface opposes the rotatable seal surface. 
The present invention also includes an improved mechanical seal comprising 
connector clips having interconnect means to be removably connected to the 
stationary components of the seal and means to interconnect to the 
housing. Preferred interconnecting means to removeably connect the 
stationary components to the connector clips are opposing pins and slots 
to receive the pins in respective stationary component and clips. The 
means to interconnect to the housing are slots to receive bolts connected 
to and extending from the housing. 
The present invention also includes an elastic sealing spring having an 
inner side, a first radial side, a second radial side and an outer side. 
The outer side has a circumferential groove having a first surface 
extending angularly from the outer side toward the inner side and a second 
surface extending from the outer side angularly toward the inner side. As 
indicated above, there can be a spring element adjacent to at least one of 
the first surface and second surface of the outer side to force at least 
one of said first outer side toward the first radial side and said second 
outer surface toward the second radial side. It is recognized that this 
elastic spring can be used to force the stationary seal element toward the 
rotable seal element or the rotatable seal element toward the stationary 
element. The latter is preferred since the elastic element can eliminate 
an "O" ring on the rotational seal element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will be understood by those skilled in the art by 
reference to the accompanying FIGS. 1-5 which illustrate preferred 
embodiments. 
The preferred mechanical seal is shown forming a seal on an apparatus, such 
as a pump, between a stationary housing 10 and a rotatable shaft 14 having 
a shaft axis 18. Housing 10 has inner surface 11 and outer surface 12. The 
shaft 14 has a shaft perimeter 20 and extends through an opening 22 in the 
housing 10. 
The mechanical seal comprises rotatable components 26 in a rotatable 
assembly and stationary components 30 in a stationary assembly. The 
rotatable components 26 are interconnected to shaft 14 by suitable means 
and rotate with the shaft 14. The stationary components 30 are 
interconnected to the housing 10 and do not rotate. The stationary 
assembly of components arid rotatable assembly of components are 
positioned relative to one another to meet at respective seal surfaces, 
i.e. a rotatable seat surface and a stationary seal surface to form a 
mechanical seal. 
The rotatable components 26 include a sleeve 34. The sleeve 34 has a shaft 
side inner wall 36 which has an inner surface having an inner perimeter 38 
which fits over the outer perimeter 20 of the shaft 14. The sleeve 34 
preferably has a radial wall 40 which extends from the inner wall 36. A 
rotatable circumferential seal element 44 is interconnected to the sleeve 
34 in order to rotate. Element 44 can be connected to sleeve 34 by any 
suitable means such as a pin or opposing slots and extensions in the 
sleeve and element 44. Preferably, sleeve 34 has extensions 45 which mate 
with opposing grooves 46 in element 44. The rotatable seal element 44 has 
a rotatable seal surface 48. The sleeve 34 can have suitable means by 
which it can be secured to the shaft 14. Such means include set screws 
(not shown) which can pass through threaded set screw holes. Additionally, 
there can be a collar 41 having holes through which the set screws pass 
and which can also be secured in place by the set screws. The various 
elements of the rotatable and stationary components can be maintained in 
place between stationary collar 41 and radial wall 40. 
The stationary assembly components 30 include a gland 52 which extends 
around the perimeter 20 of the shaft 14. The gland 52 has a gland 
component, such as gland gasket 54 located in circumferential gland gasket 
slot 55. The gland gasket can sealingly abut against the housing 10 around 
the shaft 14. A stationary circumferential seal element 56 is directly or 
indirectly interconnected to the gland 52 by suitable means such as at 
least one pin or opposing slots and extensions in the gland 52. The 
stationary seal element 56 has a stationary seal surface 58. The gland 52 
is located on the shaft 14 at a position whereby the stationary seal 
surface 58 opposes the rotatable seal surface 48. The gland 52 can be 
axially centered around shaft 14 using spacer means 53. The spacer means 
53 cam be made of a suitable material such as carbon filled 
polytetrafluoroethylene or carbon filled phenolic resin. 
A preferred stationary seal element 56 assembly is shown in FIG. 3 and 
described in U.S. Pat. No. 4,832,351, hereby incorporated by reference. 
Briefly, the stationary seal element 56 has a stationary seal extension 57 
opposite the stationary seal surface 58. The extension slideably fits into 
stationary support ring 59 slot 60. There are floating "O" rings 61 
between the extension 57 and the inner walls of the slot 60. A hydraulic 
medium such as silicon gel is located in the slot cavity 62 between the 
end of the extension and the bottom of the slot 60. A stationary seal such 
as "O" ring 63 is located between the support ring 59 and gland 52. 
Thereby, the stationary seal element 56 is self-aligning arid is axially 
stable. The seal element 56 can be attached to support ring 59 by suitable 
means such as pin 65. The support ring 59 remains stationary by suitable 
means to be attached to gland 52, but is preferably maintained stationary 
by the friction between "O" ring 63 and gland 52. 
A circumferential elastic element 64 is located around the sleeve 34 
between the radial sleeve wall 40 and the rotatable seal element 44. The 
elastic element 64 has an inner side 66 adjacent to the sleeve inner wall 
36, a radial wall side 70 adjacent to the sleeve radial wall 40, and a 
seal side 74 adjacent to the rotatable seal element 44. The elastic 
element 64 is positioned to sealingly engage and force the rotatable seal 
element 44 axially away from the radial wall 40 and toward the stationary 
seal element 56. There is an outer side 78 opposite the inner side 66. The 
outer side 78 has an outer seal side surface 82 extending for at least 
part of the circumference of the elastic element 64. The outer seal side 
surface 82 extends angularly for at least part of the axial distance from 
the outer side 74 at the seal side toward the inner side 66. Preferably, 
the elastic element 64 has an outer radial side surface 88 extending for 
at least part of the circumference of the elastic element 64. The outer 
radial side surface 88 extends angularly from the outer side 78 at the 
radial side 70 toward the inner side 66. 
In the particularly preferred embodiment illustrated in FIG. 1, the 
rotatable component assembly further comprises a rotatable chamber 90 
defined by the shaft side inner wall 36 of sleeve 34, the radial wall 40 
and a circumferential outer wall 94. The outer wall 94 extends from the 
radial wall 40 over at least part of the shaft side inner wall 36. There 
are openings 98, preferably in the outer wall 94 to permit fluid from 
inside the apparatus housing to communicate with the outer side 78 of the 
elastic element 64. The elastic element 64 is tightly squeezed between 
radial wall 40 and the rotatable seal element 44. The pressure of the 
fluid acting on outer seal surface 82 and preferably also outer radial 
side surface 88 also forces the axial floating rotatable seal element 44 
into a sealing contact with the stationary seal element 56 at their 
respective seal surfaces 48 and 58. 
The outer seal side surface 82 and outer radial side surface 88 in the 
outer side 78 of the elastic element 64 preferably define a 
circumferential groove 102 in the outer side 78. The groove preferably has 
cross-sectional shapes selected from the group consisting of "U" and "V" 
as shown in FIGS. 1, 4 and 5. 
It is desirable to have uniform pressure on radial wall side 70 and seal 
side wall 74. In order to accomplish this, particularly, where there is a 
groove 102 in the outer side 78 of the elastic element 64, there is at 
least one circumferential inner side groove 106 in the inner side 66. More 
preferably, there are two circumferential grooves 106 extending radially 
into the inner side 66. 
The elastic element 64 can further comprise a spring means to force the 
outer seal surface 82 toward the rotatable seal 44. The spring means can 
also force the outer radial surface 88 toward the radial wall 40. Useful 
and preferred spring means can include angular washers 110 and 110' to 
force onto outer seal surface 82 and optionally outer radial side surface 
88 as shown in FIG. 4. Alternatively, a circumferential spring element 
having a similar shape to groove 102 and angled toward walls 70 and 74 to 
force surfaces 88 and 82 toward those walls can be used. By angled it is 
meant that angle "x" and "y" of surfaces 82 and 88 are less that 
corresponding angle "x" and "y" of the adjacent spring surfaces before the 
springs 110 are forced into the groove 102. 
The mechanical seal of the present invention can be connected to form a 
seal between a stationary housing 10 and a rotatable shaft 14 having a 
shaft axis 18 where the shaft 14 extends through an opening 22 in the 
housing 10. Typically, there are studs or bolts 112 extending from and 
interconnected to the housing wall. The extending ends can be threaded to 
received a nut 114. Typically, there are from two to eight and more 
typically two to six bolts extending. The gland 52 can have slots or holes 
to receive the bolts 112. The bolts pass through the gland 52. The gland 
52 along with the mechanical seal are secured sealingly in place between 
the housing 10 and the nuts 114. 
In a specific and preferred embodiment of the present invention the 
mechanical seal further comprises a plurality of connector clips 120 
removably interconnected to a stationary component, preferably gland 22. 
The connection can be a tongue and groove or pin in a hole or slot 
connection. Preferably each clip 120 has a pin 122 which fits into a 
corresponding hole or slot 124 in the gland 22. Alternatively, the pin can 
extend from the gland 22 and the slot can be in the clip 120. The clip 120 
can then be put in place after the seal is installed and removed prior to 
conducting maintenance or removal of the seal. The clip 120 can have means 
to attach to the housing such as slots 126 through which bolts 112 can 
pass and be secured by nuts 114. and means to interconnect to the housing. 
The various elements of the seal of the present invention can be made of 
suitable materials to withstand the environments and conditions which must 
be encountered. Typically, commercially available elastomeric "O" rings 
can be used. The sleeve 14, gland 22, support ring 59, collar 41 and other 
related parts can be made of metal, preferably steel and most preferably 
stainless steel. One of opposing seal elements, either rotatable seal 44 
or stationary seal 56 is a hard surface made of a material such as silicon 
carbide while the other is a soft surface such as carbon. Preferably, the 
rotatable seal 44 is made of carbon and the stationary seal 56 is made of 
silicon carbide. The elastic element 64 can be made of a suitable 
elastomeric material or composite. The base elastomer can be made of 
chloroprene, nitrile rubber, EPDM or the like. 
The mechanical seal of the present invention can be adapted to virtually 
any size shaft but can typically be used and sized for shafts having 
diameters ranging from 0.5 to 12 and more typically 1 to 6 inches. 
Although the invention is described by reference to a particular 
illustrative embodiment, changes and modifications may be apparent to 
those skilled in the art without departing from the spirit and scope of 
the invention. Therefore, all such changes and modifications are 
reasonably included within the following claims.