Face seal with elastomeric axial thrust member

A shaft seal device for inhibiting any fluid flow through between two relatively rotating faces, for example, between a casing or the like stationary member and a rotary shaft or the like rotating member extending through the casing or the like stationary member. A cylindrical seal ring member made of elastomeric material is disposed between a rotary ring fluidtightly fitted onto the rotating member and a stationary ring fluidtightly fitted into the stationary member in such a manner that both the end faces thereof come in contact with the corresponding faces of the stationary member and the rotating member. The seal ring member has at least two annular grooves formed on its outer surface and ring-shaped resilient means are fitted into said annular grooves so that both the end faces of the seal ring member are forcibly thrusted against the corresponding faces of the rotary ring and the stationary ring under the influence of contractive force of the resilient means to thereby ensure fluidtightness therebetween. To reduce wearing due to the sliding contact between the end faces of the seal ring and the corresponding faces of the stationary and rotating members and thereby to improve the durability of the device a progressive seal ring made of fluororesin is fixedly secured to the end face of the rotary ring or the stationary ring.

BACKGROUND OF THE INVENTION 
The present invention relates to a shaft seal device for inhibiting any 
fluid flow through a space formed, for example, between a casing and a 
rotary shaft extending through the casing, and more particularly to a 
shaft seal device for inhibiting any fluid flow through between two 
relatively rotating faces such as the end faces of a rotary ring fitted 
onto the rotary shaft and of a stationary ring fitted into the casing. 
DESCRIPTION OF THE PRIOR ART 
As a hitherto known shaft seal device of the abovementioned type a 
mechanical seal is generally used. There have been proposed a variety of 
mechanical seal rings which are basically constructed such that a rotary 
ring fitted onto a rotary shaft or the like rotating member in an axially 
slidable manner is thrusted by means of a spring located behind the rotary 
ring until the end face of the latter comes in tight contact with the end 
face of a stationary ring fitted into a casing or the like stationary 
member, whereby fluid-tightness is ensured between the end faces of the 
rotating and stationary rings while sliding contact is maintained at the 
contact area therebetween. 
Since the rotary ring is loosely fitted onto the rotating member, there is 
necessity for disposing a sealing member on the latter. Further, since the 
spring is disposed so as to thrust the rotary ring in the axial direction, 
a large volume of axial space must be occupied by the spring. 
SUMMARY OF THE INVENTION 
Hence, it is an object of the present invention to provide a shaft seal 
device which ensures perfect fluid-tightness for inhibiting any fluid flow 
from the inside of the casing into the outside and vice versa without 
necessity for a wide space. 
It is another object of the present invention to provide a shaft seal 
device which ensures fluid-tightness irrespective of any wearing caused on 
the slidable contact face which is rotatable relative to the stationary 
member. 
According to the present invention, a cylindrical seal ring member is 
disposed between a rotary ring fluid-tightly fitted onto the rotating 
member and a stationary ring fluidtightly fitted into the stationary 
member in such a manner that one of the end faces of the seal ring member 
comes in contact with the corresponding face of the rotary ring while the 
other end face comes in contact with the corresponding face of the 
stationary ring. The seal ring member is made of elastomeric material. 
Further, the seal ring member has at least two annular grooves formed on 
its outer surface and ring-shaped resilient means such as coil spring or 
the like are fitted around the annular grooves. 
The contractive force of the ring-shaped resilient means is transformed 
into an axial force by means of which the seal ring member is elongated in 
the axial direction until both the end faces thereof are brought in tight 
contact against the corresponding end faces of the rotary ring and the 
stationary ring with a sufficiently high intensity of contact pressure. As 
a result fluid-tightness is achieved for inhibiting fluid leakage through 
between the end faces of the seal ring member and the corresponding faces 
of the rotary ring and the stationary ring. As the end faces of the seal 
ring member wear, the seal ring member is caused to axially elongate and 
thereby tight contact is still maintained between the end faces of the 
seal ring member and the corresponding faces of the rotary ring and the 
stationary ring without any danger of losing fluid-tightness. 
In accordance with a preferred embodiment of the invention, a progressive 
seal ring made of fluororesin such as tetrafluoroethylene resin or the 
like material is fixedly secured to that end face of the seal ring member 
which slidably contacts the end face of the rotary ring or the stationary 
ring. Since the seal ring member is molded of synthetic rubber or the like 
material, the progressive seal ring may be thermally adhered to it during 
the molding operation. Owing to the arrangement of the progressive seal 
ring made of fluororesin at the end face of the seal ring member, 
frictional resistance active between the sealing end faces can be 
substantially reduced, resulting in extremely reduced wearing and improved 
durability. 
In accordance with another embodiment of the invention, a progressive seal 
ring of the type mentioned is fixedly secured to the end face of the seal 
ring member in such a manner as to come in line contact with the opposing 
end face of the rotary or stationary ring with an inclined angle thereto. 
The result is that frictional resistance is further reduced while 
fluid-tightness is maintained. 
The above and other objects, features and advantages of the present 
invention will become apparent from the reading of the following detailed 
description of preferred embodiments made in conjunction with the 
accompanying drwings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Now the present invention will be described in a greater detail with 
reference to the accompanying drawings which illustrate preferred 
embodiments of the invention. 
Referring first to FIG. 1, a rotary shaft 1 includes a rotor 2 fluidtightly 
fitted thereto so as to be rotated together. The rotary shaft 1 extends 
through a bore O formed in a casing 3. 
The rotor 2 has a recess formed on its end face located opposite to the 
casing 3 so that a rotary ring 5 is firmly fitted into the recess with a 
packing 4 interposed therebetween. Further, a stationary ring 6 is also 
firmly fitted into the inner wall of the bore O of the casing 3 in such a 
manner as to ensure fluid-tightness and inhibit its rotation relative to 
the casing 3. Specifically, the stationary ring 6 comprises a flange 7 
adapted to fluidtightly abut against the end face of the casing 3, an 
outer sleeve 8 fluidtightly fitted into the inner wall of the casing 3, a 
side wall 9 exposed to the interior of the bore O and an inner sleeve 10 
extending in parallel to the rotary shaft 1 with a considerably wide 
clearance maintained therebetween. 
Onto the outer surface of the inner sleeve 10 of the stationary ring 6 is 
fitted a cylindrical seal ring 11 which is made of elastomeric material 
such as synthetic rubber or the like. The seal ring 11 has two annular 
grooves 12 and 13 formed on its outer surface each of which grooves has a 
V-shaped cross-sectional configuration. As is apparent from FIG. 1, the 
seal ring 11 has also another annular groove and corner cuts formed on its 
inner surface whereby it has a substantially W-shaped cross-sectional 
configuration. 
Around the V-shaped annular grooves 12 and 13 are resiliently fitted coil 
springs 14 and 15 of a ring form. Since the coil springs 14 and 15 are 
mounted on the annular grooves by their radial expansion, the seal ring 11 
is strained under the influence of the contractive force of the coil 
springs 14 and 15. Due to the structure of the seal ring 11 as described 
above it is subjected to a combination of the radial force and the axial 
force, the former force being effective in reducing the diameter of the 
seal ring, while the latter force being effective in elongating it in the 
axial direction. 
Further, the seal ring 11 has a progressive seal ring 17 fixedly secured 
thereto at the end part 16 located opposite to the rotor 2. The 
progressive seal ring 17 is typically made of tetrafluoroethylene resin 
with filler filled therein and it is thermally adhered to the seal ring 11 
when the latter is molded. The other end part 18 of the seal ring 11 
located in the casing 3 is adapted to come in tight contact with the side 
wall 9 of the stationary ring 6. 
As shown in FIG. 1, both the end face 19 of the rotary ring 5 and the end 
face 20 of the progressive seal ring 17 extend in the radial direction at 
a right angle relative to the axis of the rotary shaft 1. As the seal ring 
11 is strained inwardly in the radial direction under the contractive 
force of the coil springs 14 and 15, the end part 16 of the seal ring 11 
becomes effective in thrusting the progressive seal ring 17 toward the 
rotary ring 5 until both the end faces 19 and 20 are brought in tight 
contact with one another. Further, the end part 18 of the seal ring 11 is 
thrusted against the side wall 9 of the stationary ring 6 so that 
fluid-tightness is ensured therebetween. At the same time the inner 
surface of the seal ring 11 is thrusted against the outer surface of the 
inner sleeve 10 of the stationary ring 6 so that fluid-tightness is 
ensured also therebetween. 
As the rotary shaft 1 is rotated, the rotor 2 and the rotary ring 5 are 
caused to rotate together with the rotary shaft 1. On the other hand, the 
progressive seal ring 17 is kept so as not to be substantially rotated due 
to the arrangement that it is fixedly secured to the seal ring 11 which is 
in turn brought in tight contact with the stationary ring 6 firmly fitted 
into the casing 3. Thus, though the end face 19 of the rotary ring 5 is 
rotatable relative to the end face 20 of the progressive seal ring 17, no 
fluid leakage takes place at the end faces 19 and 20, because they are 
brought in fluidtight sliding contact with one another under the influence 
of the contractive force created by the coil springs 14 and 15. As a 
result a slidable seal face S is constituted in cooperation of the end 
faces 19 and 20. 
The seal face S wears increasingly as sliding operation continues. However, 
since the end part 16 of the seal ring 11 is normally thrusted toward the 
end face 19 in the axial direction under the influence of the resilient 
force of the coil springs 14 and 15, the progressive seal ring 17 is 
caused to move toward the rotary ring 5 whereby the seal face S can be 
kept in the tight contact state. 
Next, FIG. 2 illustrates a modified embodiment of the present invention and 
the same or similar members and parts as those in the preceding embodiment 
as illustrated in FIG. 1 are identified with the same reference numerals. 
Thus, their repeated description will be not required. 
Referring to FIG. 2, the rotary ring 5' is made of ceramic material. The 
rotary ring 5' is rotated together with the rotary shaft 1 and the rotor 2 
in the same manner as in FIG. 1. 
The seal ring 11' has a progressive seal ring 17' fixedly secured thereto 
as its end part 16' located opposite to the rotary ring 5', said 
progressive seal ring 17' being made of tetrafluoroethylene resin. It 
should be noted that the end face 20' of the progressive seal ring 17' 
extends at a certain inclination angle relative to the end face 19' of the 
rotary ring 5' so that the progressive seal ring 17' comes only in contact 
with the end face 19' at the radially outermost peripheral edge thereof. 
This causes the progressive seal ring 17' to come in line contact with the 
rotary ring 5', resulting in reduced frictional resistance generated 
during rotating movement of the latter while it comes in sliding contact 
with the former. The wedge-shaped space formed between both the end faces 
19' and 20' serves as a lubricant storage, providing further reduction of 
frictional force, less wearing and improved durability. 
In this modified embodiment, the seal ring 11' has a plurality of axially 
extending grooves 21 formed on its inner wall located adjacent to the 
rotary ring 5', said grooves 21 being arranged in an equally spaced 
relation to one another in the peripheral direction. The arrangement of 
the grooves 21 makes it easier to displace the end face 16' of the seal 
ring 11' toward the rotary ring 5' under the compressive force imparted by 
the coil springs 14 and 15 as the progressive seal ring 17' wears. 
As will be readily understood from the above description, the shaft seal 
device in accordance with the present invention is constructed such that 
the optimum thrust force is developed between the one end face of the seal 
ring and the end face of the rotary ring as well as between the other end 
face of the seal ring and the end face of the stationary ring with the aid 
of resilient means such as ring-shaped coil spring or the like. Thus, the 
shaft seal device requires an axial space smaller than that of 
conventional mechanical seal using an axially acting spring means. 
Further, the seal ring has at least two annular grooves formed on the 
outer surface for easily flexing so that the shaft seal device has an 
increased axial elongation as well as an increased allowable amount of 
wearing and thereby a certain amount of axial error caused during 
assembling operation is readily corrected. It should be added that the 
shaft seal device is easily assembled on the rotary shaft. 
Further, due to the excellent flexibility of the seal ring, sufficiently 
high sealing pressure is obtainable even with a relatively soft 
ring-shaped resilient means and moreover the whole shaft seal device can 
be constructed in a small size by employing the ring-shaped resilient 
means having small dimensions. 
While the present invention has been described merely with respect to the 
illustrated embodiments, it should be of cource understood that the 
invention should be not limited only to them but various changes or 
modifications may be made within the scope as defined in the appended 
claims.