U.S. patent number 3,811,690 [Application Number 05/291,756] was granted by the patent office on 1974-05-21 for seal.
Invention is credited to Maurice J. Moriarty.
United States Patent |
3,811,690 |
Moriarty |
May 21, 1974 |
SEAL
Abstract
An improved seal primarily for piston ring use wherein leakage
is minimized by means of a seal member overlaying the end gap of
the ring member and a ridge on the ring member to prevent flow of
fluids past the end portion of the seal member. Fast seating, low
friction, and long life are provided by selection of materials and
dimensions.
Inventors: |
Moriarty; Maurice J. (Phoenix,
AZ) |
Family
ID: |
26746634 |
Appl.
No.: |
05/291,756 |
Filed: |
September 25, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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66333 |
Aug 24, 1970 |
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Current U.S.
Class: |
277/494 |
Current CPC
Class: |
F16J
9/18 (20130101) |
Current International
Class: |
F16J
9/00 (20060101); F16J 9/18 (20060101); F16j
009/16 () |
Field of
Search: |
;277/192-194,218,219,165,195,197 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Martin, Jr.; William D.
Assistant Examiner: Smith; Robert I.
Attorney, Agent or Firm: Drummond; William H. Flickinger;
Don J.
Parent Case Text
This application is a continuing application of my prior
application Ser. No. 66,333 filed Aug. 24, 1970 on "Improved Seal"
and now abandoned.
Claims
Having fully deccribed the invention in such manner as to enable
those
1. A piston ring assembly shaped and dimensioned to be received in
a piston groove to provide an improved low-friction seal between
said piston and the cooperating cylinder wall against the leakage
of combustion gases generated in the combustion chamber above said
piston and to maintain the effectiveness of said seal as the
cylinder enlarges and distorts due to wear, said improved piston
ring assembly comprising:
a. a severed annular sealing ring, said ring member being
elastically expansive to exert outwardly directed pressure against
said cylinder wall;
b. means defining a notch under the top surface of said sealing
ring member, said notch having a horizontal surface extending
radially inwardly from the periphery of said ring member and a
vertical surface spaced from the inside diameter of said ring
member; and
c. a severed elastically expansive circular gap seal member sized
to be received within said notch,
said gap seal member having a radial thickness less than the
horizontal distance of said notch
the peripheral surface of said gap seal member being substantially
more resistant to frictional wear than the peripheral surface of
said ring
2. The piston ring assembly of claim 1, wherein said gap seal
member is less elastically expansive than said seal ring member.
Description
BACKGROUND OF THE INVENTION
This invention relates to an improved seal.
More particularly, it relates primarily to shaft or cylinder type
seals, especially piston rings.
In a further aspect, the invention concerns a seal of the above
type which eliminates or minimizes flow of fluids past the
seal.
In seal applications of the type having similar problems to piston
rings in internal combustion engine applications, it is highly
important to minimize the flow of fluids past the seal. In internal
combustion engines, flow past the piston rings during the
compression cycle not only lowers the effective compression
obtained in the cylinder, but also allows raw fuel mixture to enter
the crankcase, and either creates additional pollution and
efficiency problems or requires the use of additional equipment to
re-cycle the unburned fuel. Leakage during the combustion cycle not
only detracts from power and efficient combustion, but also,
similarly, produces crankcase emissions and pollution and
re-cycling problems to handle.
Piston rings in use today are not continuous seals but have an open
junction known in the industry as the "end-gap" of the ring. Flow
through the end-gap is, of course, related to the dimensions of the
gap. Within practical limits an effort is made in the industry to
minimize this end-gap in new installations within the limits of
providing adequate tolerances for machining and metal growth. As
the encasing cylinder walls and the seal are in use, the one piece
piston ring expands to continue to do its seal job. As this
expansion occurs the end-gap becomes wider and flow of fluids
through the end-gap eventually reaches a magnitude where it becomes
imperative to replace the piston ring.
The use of such seals in most applications is of such frequency and
magnitude that economic practicability is of extreme importance. In
the past attempts have been made to minimize the end-gap problems
by use of a multiple number of rings with the respective end-gaps
of the rings in a "baffle" type alignment, but the use of
additional seals not only increases cost but also adds to the
operating friction of the assembly, which is undesirable. Past
techniques for elimination or drastically minimizing the end-gap
have been unworkable grossly uneconomical, or have required the use
of materials unsuited for many uses and not standard in the
industry.
In addition to the mentioned problem of the leakage rate of present
piston rings continuously increasing during the life of the ring,
dimensional differences in the ring because of its temperature
produce such problems as extreme leakage through the end-gap at
certain times, such as cold starting. Additionally, it is very
important in providing a solution for the mentioned end-gap
problems not only to maintain the required material and cost design
flexibility, but also to maintain or improve other desired features
of present piston rings such as their necessary spring capability,
the provisions for gas pressure loading of the seal, low friction,
long wear life, and early seating.
It would be highly advantageous, therefore, to provide an improved
seal in which end-gap leakage is effectively eliminated or
minimized by constructions adaptable to the desired materials and
which are completely economically feasible.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object and feature of the present
invention to provide an improved seal without end-gap leakage.
Another object and feature of the present invention is to provide a
piston ring with improved sealing capability.
A further object and feature of the present invention is the
provision of a piston ring type seal which has extreme design
flexibility in selection of desired materials, has ecomonic
feasibility, easy seating, long life, and low friction.
Yet another object and feature of this invention is to provide an
improved piston ring capable of obtaining a small, relatively
constant leakage rate over the entire life of the ring.
Also, an additional object and feature of the present invention is
to provide sufficient design flexibility so that the seal may be
either pressure loaded or not, depending upon the desired
application, and where such loading may be done in a desired
direction.
A still further object and feature of the invention is to provide
an effective piston ring throughout an extreme temperature
range.
An additional object and feature of this invention is to provide a
piston ring type seal which is so effective that only one seal need
by used in applications where multiple rings are currently
standard, thus reducing operationg friction.
Briefly, to accomplish the desired objectives of my present
invention, in accordance with a preferred embodiment thereof, I
first provide a piston ring member of relatively standard
construction except that it contains a flat annular notch around a
corner of the ring. An annular gap seal member dimensionally
adapted to fit in said notch is located in the notch and overlays
the end-gap of the piston ring to provide continuous sealing
capability against "blow by" around the entire periphery of the
ring. The material of the ring adjacent the notch provides a ridge
which prevents gases from getting by my improved seal by means of
entering the ring land area through the end-gap of the ring and
exiting therefrom past the end of the gap seal member, since the
ridge blocks the gases in the ring land area and does not allow
further passage. These trapped pressures in the ring land area may
be allowed to enter this area, however, for the purposes of
providing gas pressure loading of the piston rings.
Additional preferred embodiments of the present invention allow the
prevention of such gas pressure loading if not desired and further
provide systems for securing gas pressure loading seal capability
with pressure in either direction, as for example the providing of
efficient sealing during both the compression and intake cycles of
an internal combustion engine, where the directions of pressure are
opposite during these respective cycles.
A highly preferred embodiment is one in which the gap seal member
is substantially harder with respect to friction wear than the ring
member, providing low friction and long life. Additionally, if the
annular thickness of the gap seal member is made less than the
annular thickness of the ring member notch, easy and rapid seating
of the seal is obtained without loss of good long term wear
characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
Further and more specific objects, features and advantages of the
present invention will become readily apparent to those skilled in
the art from the following detailed description thereof, taken in
conjunction with the drawings, in which:
FIG. 1 is an upper perspective view of a piston ring of present
design.
FIG. 2 is a partial perspective view, partially in section, showing
the end-gap portion of a present piston ring in a ring land of a
piston encased in a cylinder and illustrating "blow by" gas
flow.
FIG. 3 is an upper exploded perspective view of a preferred
embodiment of the present invention.
FIG. 4 is an upper perspective view of the embodiment of FIG. 3 in
assembled condition.
FIG. 5 is a partial perspective view, partially in section, showing
the embodiment of FIG. 3 in a ring land of a piston encased in a
cylinder and illustrating the effective blockage of gas flow.
FIG. 6 is an exploded partial perspective view of another preferred
embodiment of the present invention.
FIG. 7 is a partial perspective view, partially in section,
illustrating yet another preferred embodiment of the present
invention.
FIG. 8 is a partial perspective view, partially in section,
illustrating yet an additional preferred embodiment of the present
invention.
FIG. 9 is an exploded partial perspective view illustrating yet
another preferred embodiment of the present invention as a
modification of the embodiment of FIG. 3.
FIG. 10 is a partial perspective view, partially in section,
illustrating yet an additional preferred embodiment of the present
invention.
FIG. 11 is a partial perspective view, partially in section,
similar to FIG. 5, but illustrating a highly preferred embodiment
of the present invention, in conjunction with FIGS. 12 and 13.
FIG. 12 is a sectional view through the section 12--12 of FIG. 11,
illustrating said highly preferred embodiment shortly after
installation of the piston ring.
FIG. 13 is the same view as FIG. 12, but illustrates said highly
preferred embodiment after the initial seating period.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Turning now to the drawings, in which the same reference numerals
indicate corresponding elements throughout the several views, FIG.
1 illustrates a piston ring 21 of the type presently being used
commercially. The end-gap 22 allows the ring to be mounted in ring
land of the piston and then compressed into place so that bearing
surface 23 is urged by the spring loading of compressed piston ring
21 against the cylinder wall. (In the present drawings the relative
sizes of the various end-gaps shown are magnified for ease of
understanding, over what these end-gaps would normally be when the
piston rings are in their compressed state.)
FIG. 2 illustrates a piston 24 having a piston ring land 25. Piston
24 is encased in cylinder 26 and a portion of combustion chamber 27
is shown in the area above the upper surface 28 of piston 24. Arrow
29 illustrates the direction of gas pressure and flow through
end-gap 22 of commercial piston ring 21 (shown mounted in piston
ring land 25) during the compression, combustion and exhaust
cycles. This flow, in addition to any gas flow between bearing
surface 23 and cylinder 26, is known in the art as blow-by.
FIG. 3 illustrates a presently preferred embodiment of the present
invention prior to assembly. Ring member 30 is similar to piston
ring 21 but having certain modifications as hereinafter described.
Shown below ring member 30 is a gap seal member 31. Ring member 30
has an end-gap 32 therein and a continuous cylindrical notch 33
(shown around the lower, outer portion of ring member 30) therein
of a size to accommodate gap seal member 31. Gap seal member 31
contains end-gap 34.
FIG. 4 illustrates the embodiment of FIG. 3 after assembly. Notch
33 as shown includes a horizontal surface 35 and a vertical surface
36. Gap seal member 31 includes an internal surface 37 and an upper
horizontal surface 38. When assembled, the bearing surface of this
described preferred embodiment consists of bearing surface 39 of
ring member 30 and bearing surface 40 of gap seal member 31. In
use, bearing surfaces 39 and 40 are in contact with the cylinder
wall. When so assembled, internal surface 41 of ring member 30
becomes the internal surface of the entire assembled piston ring
42. The arrow 43 illustrates the path and direction of gas pressure
of flow through the ring 42. It is noted that the end-gap has been
eliminated and, although in the first instance gas is free to flow
through end-gap 32 to the internal surfaces of piston ring 42, the
gas path is then effectively block by surface 41 and cannot escape
to the area beneath ring 42 through end-gap 34.
The described blockage of blow-by is clearly illustrated in FIG. 5
wherein the preferred embodiment as described and shown is
installed in a piston in a similar view to that of FIG. 2. Arrow 44
indicates the direction of gas pressure and the effective stoppage
of blow-by.
FIG. 6 illustrates another embodiment of the present invention and
shows a portion of improved piston ring 45. Piston ring 45 has two
parts, ring member 46 and gap seal member 47. The portion of ring
member 46 not illustrated is merely a continuous portion of ring as
in a standard piston ring. Cylindrical notch 48 having end surfaces
49 is located in the upper outer portion of ring member 46. Gap
seal member 47 (substantially a segment of an annulus in shape)
fits within notch 48 and is free to move circularly therein. The
ends 50 of gap seal member 47 contact the end surfaces 49 of notch
48 to prevent excess movement of gap seal member 47, thus ensuring
that end-gap 51 of ring member 46 is covered to prevent blow-by at
all times in similar manner to the embodiment of FIG. 3 described
above. Although the embodiment of FIG. 6 retains the many
discovered technical and performance advantages of multiple-piece
construction, the embodiment of FIG. 6, not only in terms of
performance but for the many obvious cost and manufacturing
advantages inherent in such construction.
FIG. 7 illustrates an alternate construction of another preferred
embodiment, similar to the embodiment of FIG. 3 but being a three
piece structure. The improved piston ring assembly 52 includes ring
member 53, upper gap seal member 54 and lower gap seal member 55.
Gap seal member 54 and 55 are similar in construction to gap seal
member 31. Ring member 53 includes both upper and lower cylindrical
notches to receive gap seal members 54 and 55 as illustrated.
Although the gas pressure loading characteristics of the embodiment
of FIG. 7 are not as good as the embodiments described
hereinbefore, such embodiments efficiently seal blow-by in either
direction of pressure in applications where the same is
important.
FIG. 8 illustrates another improved piston ring assembly embodiment
56, having similar operation characteristics to the embodiment of
FIG. 7 but construction more similar to FIG. 6. Piston ring 56
includes ring member 57 having an end-gap 58 therein, upper gap
seal member 59 located in upper notch 60 of ring member 57, and
lower gap seal member 61 located in lower notch 62 of ring member
57.
FIG. 9 shows a modified structure of the embodiment of FIG. 3 and
includes modifications both to ring member 30 and gap seal member
31. It is important in the present invention that there be no
alignment of end-gap 34 of gap seal member 31 and end-gap 32 of
ring member 30. Furthermore, it has been found that for ease of
assembly and operation the relative spacing of said end-gap one
from the other is a factor preferable to be controlled, primarily
to maximize spring expansion characteristics. In the illustrated
preferred embodiment for setting and controlling the same, a tab 63
is located on gap seal member 31 at the preferred spacing from
end-gap 34. Tab retainer notches 64 are located at both ends of
end-gap 32 on the upper portion of the internal survace of ring
member 30 as shown to receive tab 63. The presently preferred
spacing of said end-gaps is approximately 45.degree.. The end-gaps
should obviously not overlap and the preferred upper limit of such
spacing is 90.degree..
FIG. 10 is a view similar to the views of FIG. 2 and FIG. 5
illustrating a preferred embodiment of the present invention
residing in the relative structure and location of the parts shown.
Beneath piston ring land 25, carrying piston ring 42, is shown
lower piston ring 65 in piston ring land 66. Piston ring 65 is like
piston ring 42 except that it is placed in piston ring land 66 in
an upside soen position to the placement of piston ring 42. To
illustrate one advantage of this arrangement, arrow 67 shows the
direction of pressure and gas glow from combustion chamber 27
during the compression, combustion and exhaust cycles of a
four-cycle internal combustion process. Arrow 68 illustrates the
direction of pressure and gas flow during the intake cycle. Thus,
piston ring 42 is gas pressure loaded during the combustion,
compression and exhaust cycles and piston ring 65 is similarly,
because of its reversed position, gas pressure loaded during the
same may be desired.
FIG. 11 illustrates, in a similar manner to FIG. 5, an embodiment
of the type of FIG. 3 shown installed in piston 24 and bearing on
the wall of cylinder 26. Gap seal 31 is shown in position in ring
member 30, in the top ring position and in its preferred placement,
that is, on the underside of ring 30. In the embodiment, highly
preferred, now being illustrated gap seal member 31 is made
substantially harder with respect to friction wear than ring 30.
For example gap seal member 31 may be made of high carbon steel
chrome plated on its bearing surface with cylinder 26, and ring 30
may be cast iron.
FIG. 12 illustrates, by way of showing section 12--12 of FIG. 11,
the detailed relationship of the parts during operation. FIG. 12
shows this particular cross section as it looks right after
installation of the piston ring.
Ring member 30 is elastically expansive and there is bearing
pressure being exerted along that portion of bearing surface 71
between ring member 30 and cylinder 26. Gap seal member 31 is
slightly elastically expansive but not so much so as ring member
30. Thus, there is only a very slight bearing pressure along
bearing surface 70 between gap seal member 31 and cylinder 26.
Surfaces 37 and 36 are not at this point touching since, for
reasons to be hereinafter set out, the radial thickness of gap seal
member 31 (that is the distance from surface 37 to surface 70) is
made less than the radial thickness of the notch in ring member 30
(that is, distance between surface 36 and surface 70). Thus when
the instant embodiment of the present invention is installed the
primary bearing pressure and wear is occuring along bearing surface
71 and there is very little either friction or wear along bearing
surface 70. According to the present invention the difference
between the radial thickness of the gap seal member and the radial
thickness of the ring member notch (shown in FIG. 12 as space 69)
is made larger than the amount of material which must be worn off
ring member 30 along bearing surface 71 in order to properly and
adequately seat ring member 30 at said bearing surface 71. This
distance will normally be set between one-thousandth of an inch and
two-thousandths of an inch, and for the specific materials
mentioned as preferred in this paragraph, the optimum dimensional
difference, considering cost and production factors also, between
the gap seal member anular thickness and the ring member notch
anular thickness is approximately two-thousandths of an inch.
FIG. 13 illustrates the same embodiment along the same section as
illustrated in FIG. 12, except that it shows the relationships
among the parts when the initial seating of the seal of the present
embodiment has taken place and surface 36 is riding along surface
37. At this point the outward radial bearing pressures of ring
member 30 are transmitted by surface 36 at the ridge of ring member
30 to gap seal member 31. Since gap seal member 31 is substantially
harder than ring member 30, a much larger unit bearing pressure is
exerted along bearing surface 70 than along bearing surface 71. It
is now seen that this highly preferred embodiment of the instant
invention will have, during most of its life time, easy seating
(not much friction initially at bearing surface 70), low friction
(heavy unit bearing pressure only by the gap seal member at surface
70 and very light contact at surface 71), excellent sealing (a
large bearing contact area along bearing surface 71 maintained in
good contact even at low pressure), excellent wear rate (the harder
material of the gap seal member drastically slows down the rate of
wear of the assembled piston ring), no decrease in sealing
performance with wear (where the gap seal member and ring member
are both made of uniform materials, one would practically have to
break or disintegrate the ring to get any appreciable deterioration
in sealing with wear).
The sealing capabilities of the piston ring in the present
invention are so much greater than those of standard piston rings
that one piston ring will suffice in most applications with
multiple piston rings are now being used. It is preferred, in the
case of using a single piston ring, or for the case of the upper
piston ring of several, that the gap seal member be located on the
side of the ring member away from the combustion chamber, since the
heat of the combustion chamber is better borne by the ring member.
This is especially true when the ring member is composed of its
preferred material, cast iron, and gap seal member is composed of
its preferred material, steel (usually chrome plated).
Various changes in the embodiments herein chosen for purposes of
illustration in the drawings will readily appear to persons skilled
in the art having regard for the disclosure herein. To the extent
that such modifications and variations do not depart form the
spirit of the invention, they are intended to be included within
the scope thereof which is not limited to the embodiments
specifically illustrated, but rather only a fair interpretation of
the following claims.
* * * * *