U.S. patent number RE32,395 [Application Number 06/766,247] was granted by the patent office on 1987-04-14 for piston and piston rings set.
Invention is credited to Christophe Geffroy, Robert Geffroy.
United States Patent |
RE32,395 |
Geffroy , et al. |
April 14, 1987 |
Piston and piston rings set
Abstract
New assembly of cylinder, lightweight piston and piston rings
for engines and compressors comprising in a cylinder a reduced
weight piston provided with a new simpler piston rings set of a
high efficiency producing a very small tension against the cylinder
and lighter than the piston rings set known heretofore and wherein
each of the purposes ascribed to the individual piston rings of the
set is entirely attained by each piston ring of this assembly.
Inventors: |
Geffroy; Robert (Neuilly s/s
Maillot 38-57, Paris, FR), Geffroy; Christophe
(Neuilly s/s Maillot 38-57, Paris, FR) |
Family
ID: |
27251036 |
Appl.
No.: |
06/766,247 |
Filed: |
August 16, 1985 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
344732 |
Feb 1, 1982 |
04516481 |
May 14, 1985 |
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Foreign Application Priority Data
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Feb 6, 1981 [FR] |
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81 02353 |
Dec 23, 1981 [FR] |
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81 24100 |
Jan 15, 1982 [FR] |
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82 00625 |
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Current U.S.
Class: |
92/212;
123/193.6; 277/446; 277/486; 277/488; 277/946; 92/158; 92/240;
92/246 |
Current CPC
Class: |
F16J
9/16 (20130101); F16J 9/20 (20130101); F16J
9/00 (20130101); F05C 2201/0448 (20130101); F05C
2225/04 (20130101); Y10S 277/946 (20130101) |
Current International
Class: |
F16J
9/00 (20060101); F16J 9/16 (20060101); F16J
9/20 (20060101); F16J 001/04 (); F16J 009/20 ();
F16J 015/32 () |
Field of
Search: |
;92/193,194,160,212,240,246,241,245,158,159 ;123/193P
;277/216,139,148,220,24,212C,152 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0826487 |
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Mar 1938 |
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FR |
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0869831 |
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Feb 1942 |
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FR |
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008957 |
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1915 |
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GB |
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0123351 |
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Jul 1919 |
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GB |
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1126457 |
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Sep 1968 |
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GB |
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635333 |
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Nov 1978 |
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SU |
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Primary Examiner: Look; Edward K.
Attorney, Agent or Firm: Forster; Lloyd M.
Claims
We claim:
1. An assembly comprising a cylinder, for internal combustion
engine or compressor, extending between a compression head and a
crankcase, a piston, and piston rings set reciprocable within said
cylinder characterized by an improved combination of compression
ring and oil control ring means for reducing friction, blow-by, and
oil climbing, said means comprising: compression ring means in a
piston groove coaxial with the cylinder adjacent the compression
head end of said piston for minimizing blow-by from said
compression head to said crankcase, and oil control ring means in a
piston groove adjacent said compression ring means on the crankcase
side constructed with acute conical elastic circular outer edge
skirt means projecting uniformly from its piston groove for
differentially scraping oil from the cylinder wall during the
strokes of the piston toward said crankcase, and for bypassing oil
on the cylinder wall by Kingsbury effect during strokes of the
piston away from said crankcase, said skirt means comprising a
plurality of separated metal blades projecting from an integral
connecting portion of said oil control ring means, the composite
free state circumference of said blades being greater than their
operating circumference thereby providing said outward spring bias
upon assembly.
2. The assembly of claim 1 wherein said compression ring means
comprises at least one thin radially cut ring of elastic metal the
circular lip of which is applied against the cylinder by its
elastic over size free state and wherein closing means is provided
for sealing off passage of gas through clearance at the radial cut
of the ring.
3. The assembly of claim 2 wherein said elastic metal ring means is
provided with substantial sufficient end separation, and said
closing means comprises a ring segment of compressible elastic
plastic material capable of filling the gap at said radial cut of
the metal ring under thermal conditions of minimum ring extension
and of absorbing without permanent deformation the expansion of
said ring extension under thermal conditions of maximum metal ring
extension.
4. The assembly of claim 2 or 3 including at least one thin cut
supplemental ring of plastic material adjacent said metal ring in a
piston groove on the crankcase side of said metal ring, said
plastic ring having a circumferential dimension providing elastic
contact with said cylinder free of any end clearance gap throughout
all thermal conditions of operation.
5. The assembly of claim 2 wherein said metal ring means includes
two adjacent thin cut metal rings with means for retaining their
respective end gaps in circumferentially spaced relation.
6. The assembly of claim 5 wherein said last means comprises
inter-engaging notch and projection means formed in the respective
rings to prevent relative circumferential displacement without
otherwise restricting independent engagement with the cylinder
wall.
7. The assembly of claim 2 or 3 including a plurality of notches
around the inner edge of said ring adapted to increase the radial
flexibility for a given radial thickness appropriate for stable
piston groove engagement.
8. The assembly of claim 2 or 3 wherein adjacent partial radial
cuttings extending respectively from the outer and inner edges of
the metal ring means are provided at a plurality of
circumferentially spaced locations which contribute an elastic
compressibility of ring segments' circumference to accommodate
variable thermal operating conditions, said ring segments being
provided with a free form curvature substantially equal to said
cylinder wall biased resiliently outwardly beyond operating
circumference in the free state through the ring connections
between said partial cuttings, and being adapted to substantially
close said partial cuttings under operating conditions of maximum
thermal expansion of said compression ring means.
9. The assembly of claim 8 wherein said metal ring means is
provided with at least one through cut intermediate said partial
cuts adapted to accommodate assembly in an integral piston groove,
the ends of any complete cutting being held in engagement
throughout all thermal operating conditions by the spring bias
provided through said partial cuttings.
10. The assembly of claim 1 wherein separation between said blades
upon assembly is only sufficient to provide controlled calibrated
passage for lubricating oil together with accommodation for thermal
expansion of said oil control ring means.
11. The assembly of claim 10 wherein said connecting portion
comprises a radially extending flat ring portion.
12. The assembly of claim 10 wherein said connecting portion
comprises a cylindrically extending portion bonded to a cylindrical
portion of said piston.
13. The assembly of claim 11 wherein said oil control ring means
has a through radial cut to accommodate assembly within an integral
piston groove.
14. The assembly of claim 11 wherein the connecting portion of said
ring is integral without through radial cut for use in a
multi-piece piston separable at the location of the oil control
ring groove.
15. The assembly of claim 1 wherein separation of said blades is
inclined to the axis of said piston to provide a ring rotating bias
during operation.
16. The assembly of claim 11 wherein said connecting portion is
provided with a plurality of uniformly distributed radially
extending cuts intermediate the separation of said blades.
17. The assembly of claim 16 wherein said radial extending cuts are
equal in number and central between separation of said blades.
18. The assembly of claim 1 wherein said compression ring means
includes at least one thin cut ring of elastic metal the circular
lip of which is applied against the cylinder by its elastic
oversize free state, closing means for sealing off passage of gas
through the clearance of the cutting, at least one thin cut ring of
plastic material 26, 76 the circular lip of which is applied
against the cylinder through the effect of its circumference with
both ends 715 in contact, said rings being disposed with a small
clearance 27 in a groove of a piston, and said ring 26, 76 of
plastic material being disposed between the grooved face of the
piston 21 on the side of the crankcase and said metal ring 25,
35.
19. The assembly of claim 1 wherein said oil control ring means is
made of one-piece spring steel formed with a circular row of thin
elastic lateral blades 1117, 1217, 1317, 1417, 2117, 2217 connected
between one another and to the piston by the common side of their
row 1118, 1218, 1318, 1418, 2018, 2118, 2218 located on the side of
the piston head, and said blades being applied against the cylinder
134, 144 by the edge of their row located on the side of the
crankcase through the elastic force of each blade, their outer
lateral faces making with the wall of the cylinder an acute conical
angle .alpha. opening to the piston head, said blades forming
together a closed elastic skirt sealed on the side of the piston
head and open to the crankcase, said piston comprising on its
periphery, at the level of the blades of the oil ring 1317, 1417,
an annular space 1326, 1426, for collecting scraped oil and means
1327, 1429, 1330, 1431 for return thereof into the crankcase.
20. The assembly of claim 1 wherein said compression ring means
includes at least one thin cut ring of elastic metal the circular
lip of which is applied against the cylinder by its elastic
oversize free state, closing means for sealing off passage of gas
through the clearance of the cutting, at least one thin cut ring of
plastic material 26,76 the circular lip of which is applied against
the cylinder through the effect of its circumference with both ends
715 in contact, said rings being disposed with a small clearance 27
in a groove of a piston, and said ring 26, 76 of plastic material
being disposed between the grooved face of the piston 21 on the
side of the crankcase and said metal ring 25, 35, and wherein said
oil control ring means is made of one-piece spring steel formed
with a circular row of thin elastic lateral blades 1117, 1217,
1317, 1417, 2117, 2217 connected between one another and to the
piston by the common side of their row 1118, 1218, 1318, 1418,
2018, 2118, 2218 located on the side of the piston head, and said
blades being applied against the cylinder 134, 144 by the edge of
their row located on the side of the crankcase through the elastic
force of each blade, their outer lateral faces making with the wall
of the cylinder an acute conical angle .alpha. opening to the
piston head, said blades forming together a closed elastic skirt
sealed on the side of the piston head and open to the crankcase,
said piston comprising on its periphery, at the level of the blades
of the oil ring 1317, 1417, an annular space 1326, 1426, for
collecting scraped oil and means 1327, 1429, 1330, 1431 for return
thereof into the crankcase.
21. The assembly of claim 18 wherein said compression ring means
comprises at least one thin cut metal ring the outer circular lip
of which is applied against the cylinder by machining the outer
periphery in the exact shape and size of the cylinder, including
means for providing radially outward elastic bias, and closing
means for sealing off passage of gas through the clearance of the
cutting.
22. The assembly of claim 1 further characterized in that the means
for closing off the cutting comprises two thin cut rings 45, 411,
55, 611, assembled side by side and made of elastic metal the
circular lips of which are applied against the cylinder 14, 44 by
their elastic oversize free state, said rings 45 being provided
with means 512, 912, 613, 1013, 614, 1014, for preserving
independence of their movements but imposing limitation to their
circumferential location relative to each about the axis of the
piston thereby to prevent alignment of their respective
cuttings.
23. The assembly of claim 1 further characterized in that the means
for sealing off the cutting comprises relatively plastic contiguous
closing means 310, extending between substantially spaced ends 38,
39 of said ring 25, 35.
24. The assembly of any of claims 1, 2, or 3, further characterized
in that at least one thin ring of elastic metal 25, 35, 45, 411,
55, 611, 95, 1011, of the compression ring 12, 22, 42, includes
notches 916, 1016, distributed on its inner periphery.
25. The assembly of any of claims 1, 2, or 3, further characterized
in that the cutting of the oil ring comprises a closing abutment
2034, 2035, cooperating with a spacer 1322, 1522, having a
thickness 1524 at least equal to the height of ledges 2034, 2035 of
said abutment.
26. The assembly of claim 1 wherein said compression ring means
comprises at least one elastic metal ring 2337, preferably of thin
steel the cross section of which is uniform, with its periphery
accurately made to a circular form having a circumference
substantially equal to that of the cylinder, means for providing
elastic application of said ring against said cylinder comprising
at least one micro-spring 2339, 2439 consisting of at least two
partial alternate radial cuttings on the outside 2541 and the
inside 2542 of the ring, and by elongation of the circumference of
said ring 2443 in excess of the circumference of the cylinder which
when added to the clearance required for expansion of the piston
ring is at most equal to the sum of the widths of said partial
alternate radial cuttings 2541, 2542 with said widths being
determined for operation when the micro-spring(s) is (are)
compressed in the operative position in the cylinder.
27. The assembly of claim 1 wherein said compression ring means
includes at least one micro-spring 2639 comprising a coiled spring
2646 housed in holes 2647 formed in faces of the cutting(s) with an
expansion in the free state of the circumference of said ring
greater than the end clearance necessary for accommodating thermal
expansion of the piston ring.
28. An assembly according to any of claims 20, 22, or 23
characterized in that at least one thin ring of elastic metal 25,
35, 45, 411, 55, 611, 95, 1011 of the compression ring 12, 22, 42
comprises nothces 916, 1016 distributed on its inner periphery.
29. An assembly comprising a cylinder for internal combustion
engine or compressor, a piston and piston ring set, characterized
by improved means for reducing friction and oil climbing, the means
used comprising:
an oil ring means 13, 113, 123, 133, 143, 2113, 2213 for scraping
oil from the cylinder wall during the downward strokes of the
piston, and bypassing oil on the cylinder wall during the upward
strokes of the piston, said oil ring means being made of one piece
spring steel formed with a circular row of very thin elastic
touching lateral blades 1117, 1217, 1317, 1417, 2117, 2217
connected to one another and to the piston by the common side of
their row 1118, 1218, 1318, 1418, 2018, 2118, 2218 located on the
side of the piston head, and said blades being applied against the
cylinder 134, 144 by the edge of their row located on the side of
the crankcase through the elastic force of each blade, their outer
lateral faces making with the wall of the cylinder an acute conical
angle .alpha. opening to the piston head, said blades forming
together a closed elastic skirt sealed on the side of the piston
head and opened to the crankcase;
said piston comprising on its periphery, on the level of the blades
of the oil ring 1317, 1417, an annular space 1326, 1426 for
collecting scraped oil and means 1327, 1429, 1330, 1431 for the
return thereof into the crankcase.
30. An assembly according to any of claims 1, 2, 3, 20, 21, 22, 23
or 29 including compression ring means consisting of a flat thin,
uniform ring 2337 made of elastic metal, preferably, spring steel,
of which the periphery is constructed to the shape and dimension of
the cylinder, said ring having at least one cutting 2541 in contact
with the cylinder and submitted to the action of micro-spring means
2339, 2439, 2639 having a thickness not in excess of that of the
ring, said micro-spring means housed in the groove of the ring
slightly increasing the diameter in the free condition of said ring
such that when the ring is in the cylinder, the cuttings 2541, 2648
contacting the cylinder presents the required clearance for thermal
extension of the ring, said micro-spring means when compressed and
exerting upon the ring an opening force parallel to the
circumference thereof and by producing a force applying the ring
uniformly against the cylinder.
31. An assembly according to claim 30 wherein each micro-spring
2339, 2439 consists of at least two partial alternate cuttings,
outwardly 2541 and inwardly 2542 of the ring, separated by an
elastic tongue 2543.
32. An assembly according to claim 30 wherein each micro-spring
2639 consists of a helical spring 2646 housed in holes 2647 formed
in cutting faces of the ring.
33. An assembly according to claim 1 or 29 including an annular
ring 2218 of the oil ring formed with inwardly open cuttings 2236
extending at least part of the width of the ring 2218. .Iadd.
34. An assembly comprising a cylinder for internal combustion
engine or compressor extending between a compression head and a
crankcase, a piston, and piston ring set reciprocable within said
cylinder characterized by compression ring means in a piston groove
providing free axial clearance comprising at least one thin metal
ring having a plurality of separate circumferentially spaced
segments, said ring segments being provided with free form
curvature substantially equal to said cylinder wall and when in
abutting relation a free form circumference slightly greater than
operating circumference, and means for resiliently biasing said
segments outwardly beyond operating circumference in the free
state. .Iaddend. .Iadd.35. The assembly of claim 34 wherein said
means for biasing includes partial radial cuttings in the metal
ring means at a plurality of circumferentially spaced locations
which contribute an elastic compressibility of ring segments'
circumference to accommodate variable thermal operating conditions.
.Iaddend. .Iadd.36. The assembly of claim 35 wherein said metal
ring means is provided with at least one through cut intermediate
said partial cuts adapted to accommodate assembly in an integral
piston groove, the ends of any complete cutting being held in
engagement throughout all thermal operating conditions by the
spring bias
provided through said partial cuttings. .Iaddend. .Iadd.37. The
assembly of claim 36 wherein said partial radial cuttings extend
respectively from the outer and inner edges of the metal ring means
forming a plurality of micro springs 2339, 2439. .Iaddend.
.Iadd.38. The assembly of claim 37 wherein said metal ring means is
provided with three through cuts intermediate said partial cuts.
.Iaddend. .Iadd.39. The assembly of any of claims 34-38 including
at least one thin cut supplemental ring of plastic material
adjacent said metal ring in a piston groove on the crankcase side
of said metal ring, said plastic ring having a circumferential
dimension providing elastic contact with said cylinder free of any
end clearance gap throughout all thermal conditions of operation.
.Iaddend. .Iadd.40. An assembly comprising a cylinder for internal
combustion engine or compressor extending between a compression
head and a crankcase, a piston, and piston rings set reciprocable
within said cylinder characterized by improved means for reducing
friction and oil climbing, said means comprising oil control ring
means in a piston groove constructed with acute conical elastic
circular outer edge skirt means projecting uniformly from its
piston groove for differentially scraping oil from the cylinder
wall during the strokes of the piston toward said crankcase, and
for bypassing oil on the cylinder wall by Kingsbury effect during
strokes of the piston away from said crankcase, said skirt means
comprising a plurality of separated metal blades projecting from an
integral connecting portion of said oil control ring means, the
composite free state circumference of said blades being greater
than their operating circumference thereby providing said outward
spring bias upon assembly.
.Iaddend. .Iadd.41. The assembly of claim 40 wherein separation
between said blades upon assembly is only sufficient to provide
controlled calibrated passage for lubricating oil together with
accommodation for thermal expansion of said oil control ring means.
.Iaddend. .Iadd.42. The assembly of claim 41 wherein said oil
control ring means has at least one through radial cut to
accommodate assembly within an integral piston groove. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The pistons in internal combustion engines or compressors are
generally provided with a set of piston rings the purposes of which
are preventing, between pistons and cylinders, any leak of gas to
the crankcase and of oil to the piston head.
The presently known piston rings of said set interfere in operation
one with another and the assembly thereof does not insure
completely the attainment of said purposes, each of said piston
rings being incapable of playing its entire role.
The compression rings permit passage of the gas (blow-by) from the
combustion or compression chamber to the crankcase, and the oil
rings scrape in both directions, and thereby work against their
purpose in the upward stroke of the piston.
Thus, their roles are not exactly fulfilled thereby resulting in
difficult tuning, instabilities, insufficiences and uncertainties
of operation.
Finally, all said piston rings are applied with substantial force
against the cylinder and are heavy, which results in significant
energy consumption by friction and inertia.
The closest known prior art of the present invention includes the
following:
U.S. Pat. No. 2,893,797 shows a scraper ring comprising a skirt
opened to the crankcase, consisting of tongues applied to the
cylinder through the action of a compression ring mounted in the
same groove acting by tipping over upon an angled extension of such
tongues penetrating said grooves; but the tongues of this ring have
no freedom of movement on the piston and application thereof
against the cylinder which is rigid is not appropriate for an oil
scraping operation which, to be efficient, must be flexible and of
low friction.
U.S. Pat. No. 2,846,280 shows flat rings associated with plastic
rings configured as either compression rings or scraper rings, but
which do not comprise any means for providing them freedom of
movement with the piston, or contributing to efficiency or
reduction of friction.
French Pat. No. 826,487 shows compression rings composed of thin
frusto-conical ring packs comprising retaining means to prevent
their cuttings from overlapping each other and applied against the
cylinder through deformation of their cones caused by wedging them
into their groove; however, such arrangements do not ensure any
increased tightness or reduced friction.
U.S. Pat. No. 2,262,311 which shows a flat compression ring formed
with many slots therein regularly distributed on the full periphery
of the ring; above all it claims characteristics of conformability
permitting adaptation thereof to worn cylinders but does not afford
any progress in tightness or reduced friction.
French Pat. No. 869,831 shows a compression ring composed of two
flat uncut rings mounted to a piston with a dismountable head,
equipped with an application spring with a great number of slots in
contact with the cylinder obturated by blocking through two
superposed rings; here too, with such rings the cutting clearances
are obturated but no freedom of movement of the ring in its groove
is ensured and the ring does not realize any particular performance
in the domain of tightness and reduction of friction.
British Pat. No. 1,126,457 shows a spiral spring for assisting the
application force of a conventional ring against the cylinder; such
system is known to increase the tension in a conventional ring but
does not supply any novel element in the technology of piston rings
either relative to tightness or friction against the cylinder.
Related prior art also includes:
U.S. Pat. No. 3,759,148 issued Sept. 18, 1973
U.S. Pat. No. 3,831,952 issued Aug. 27, 1974
U.S. Pat. No. 3,656,766 issued Apr. 18, 1972
U.S. Pat. No. 3,840,182 issued Oct. 8, 1974
U.S. Pat. No. 2,893,675 issued July 8, 1975
U.S. Pat. No. 3,917,290 issued Nov. 4, 1975
U.S. Pat. No. 4,103,594 issued Aug. 1, 1978
French Pat. Appln. No. 81,13347 filed July 8, 1981
French Pat. No. 2,185,094
French Pat. No. 1,540,312
Gr. Britain Pat. No. 593,392
SUMMARY OF THE INVENTION
The present invention relates to an assembly comprising in a
cylinder, a reduced weight piston provided with a new simpler
piston rings set of a high efficiency producing very low tension
and friction against the cylinder, which is lighter than the piston
rings set known heretofore, wherein the compression ring elements
substantially eliminate blow-by and an oil ring scrapes in a
downward direction only to effectively recycle lubricating oil
during the upward stroke.
This invention relates to an assembly of cylinder, piston and
piston rings for internal combustion motors or compressors,
comprising a compression ring consisting of at least one flat thin
ring of metal and a one-piece scraper ring of metal consisting of a
circular portion connected through a circular fold to a lateral
circular row of blades formed into a skirt open to the crankcase
characterized in that:
The piston ring set in each piston of engine or compressor
comprises:
a compression ring consisting of at least one ring of elastic metal
the circular lip of which is applied against the cylinder by
elastic tension and which provides at least one mean for reducing
if not closing off the passage of gas between the combustion
chamber and the crankcase, on the one hand, and on the other hand,
for reducing the friction between the said ring and the
cylinder.
The compression ring consists of elastic metal, mounted in its
groove with a small lateral and axial clearance and it comprises in
itself elastic means for applying its outer lip uniformly against
the cylinder with a low force which is made possible by its regular
spreading, such force being obtained from the only effect of its
own elastic tension the cutting in said ring comprising in the
section of said thin ring means for at least reducing if not
obturating passage of gas through the cutting clearance.
a one piece oil ring of spring steel consisting of a circular row
of connective and elastic, very thin, lateral blades connected with
one another and with the piston sealingly by the edge of their row
located on the side of the piston head and applied against the
cylinder by the edge of their row located on the side of the
crankcase, by means of the elastic force of each blade, their outer
lateral faces being configured to the shape of the cylinder and
having with the wall thereof a very acute conical angle opening to
the piston head, said blades constituting together an elastic
circular skirt closed and sealed on the side of the piston head and
opening to the crankcase;
the scraper ring consists of an elastic metal and is very thin;
said circular portion is held by the piston in an invariable
angular position with respect to its axis, said circular fold
providing to the lateral blades a circular edge which is the
resting and articulation point thereof to ensure flexible
application of their lips against the cylinder by their own very
low elastic force, since they are very thin, said blades forming
with the cylinder wall an acute angle open to the piston head,
having between themselves a very small clearance which makes each
of them independent of the adjacent ones, and form together said
closed skirt sealed to the top of the piston, open to the crankcase
and held in contact with the cylinder, said contact being
permanent, elastic, very light and very narrow; and
adaptive means for accommodating the piston rings and improvements
in the piston and the cylinder.
Such an assembly makes a very simple piston rings set and it is
less cumbersome and less heavy than the piston rings set known
heretofore. The compression ring ensures highly efficient control
of the passage of gases between the combustion or compression
chamber and the crankcase, and the oil ring produces two new
actions of very high efficiency, the one being a simple effect
scraping during the downward stroke of the piston and the other a
simple effective recycling during the upward stroke of the
piston.
As a matter of fact, in the downward strokes the lower edge of its
outer thin and elastic face nearly parallel to the cylinder
constitutes an ideal means for scraping off oil, even though its
application force on the cylinder is minimum and in the upward
strokes the small angle with the cylinder of the wall of its outer
face constitutes another ideal planing device wherein its
application force on the cylinder is still minimum to recycle,
toward the crankcase by dynamic effect, oil subsisting on the
cylinder wall.
Moreover, the high and independent efficiency of each of these
piston rings creates more favorable conditions for the operation of
the other than the previously known mutual interraction. Thus, the
purposes attributed to the piston rings set are reached with a high
efficiency than by the usual piston rings set, with lesser wear and
greater saving of energy. Finally, this better efficiency of each
of the piston rings and the smaller friction thereof results in an
entirely new lubrication method between piston, piston rings and
cylinder, which produces several new operational conditions:
the possibility of adopting for the cylinder walls a polishing
level much higher than the usual level thereby to produce further
reduction of friction and wear in all the members of said new
assemblies which are a supplementary contribution to the savings of
energy.
The possibility of establishing the mechanical bearing between the
cylinder and the piston up to the piston head, thereby to improve
thermal exchanges between cylinder and piston and also due to the
fact that it comprises only two piston rings, to permit shortening
and thus significant lightening of the piston.
Other characteristics and advantages of this invention will appear
from the following description of an assembly according to the
invention in the light of the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents, in a cut off cylinder, a piston provided with a
piston ring consisting of a compression ring and an oil ring;
FIG. 2 and FIG. 4 are cross-sectional views in enlarged scale of a
portion of the piston, showing alternate embodiments of a
compression ring, in a cylinder;
FIG. 3 shows means to close off passage of gas through the
separated ends of a compression ring;
FIGS. 5, 6 and 7 are planar views of three rings constituting the
composite compression ring of FIG. 4;
FIG. 8 is a cross-sectional view in enlarged scale taken along line
A--A of FIGS. 5 and 9;
FIGS. 9 and 10 are planar views of a variation of the rings of
FIGS. 5 and 6;
FIGS. 11 and 12 are perspective views of an oil ring and a
variation thereof;
FIGS. 13 and 14 are cross-sectional views of a piston portion, each
showing the section of the oil ring of FIGS. 11 and 12 in its
operative position;
FIG. 15 is a perspective view of an annular spacer for an oil
ring;
FIGS. 16 and 18 are two lateral views of an oil ring of FIG. 11 and
modification thereof in the free position;
FIGS. 17 and 19 are cross-sectional views of FIGS. 16 and 18;
FIG. 20 is a perspective view of gap ledges added to an oil ring of
FIGS. 11, 13 and 16;
FIGS. 21 and 22 are perspective views of variations of the ring
illustrated in FIG. 11;
FIGS. 23 and 24 are views of a variation of a compression ring;
FIGS. 25 and 26 are respectively an enlarged fragmentary view of
the micro-spring included in the compression ring of FIGS. 23 and
24 and an example of a modified form of micro-spring.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a composite compression ring 12 and an oil ring 13 on
a piston 11. Such assembly is disposed in a cylinder 14. After
describing those piston rings and explaining the working of said
assembly, the specificites of the piston and the cylinder which are
rendered possible by using said piston rings, will be explained
further.
FIG. 2 shows in a partial cross-section of the piston 21 in its
cylinder 24 a first form of embodiment of a compression ring 12,
22. It is composed of two thin elements 25 and 26 disposed with
clearance 27 in the groove of piston 21. Such clearance 27 is
limited to the minimum necessary for ensuring freedom of movement
of both thin elements as well as access of the pressure from the
combustion or compression chamber through the clearance 27 on the
top and on the inner cylindrical face of piston ring 22.
The thin elements of piston ring 22 are a thin cut ring 25
(thickness of about 0.7 mm) of elastic metal, e.g. cast iron or
steel, on the one hand, and on the other hand, a thin cut ring 26
(thickness of about 0.5 mm) of a relatively plastic material, such
as annealed copper or polytetrafluoroethylene (Teflon). The plastic
ring 26 is always disposed between the ring of elastic metal 25 and
that groove face of the piston which is on the crankcase side.
The ring 25 in the free position has a diameter larger than that of
the cylinder to make it capable of having an expansion force
against the cylinder and the closing off of the gas passage by the
substantial end clearance along the wall of the cylinder is ensured
by the arrangement shown on FIG. 3; ring 25 is represented thereon
in a plan view at 35 in its tightened position in its cylinder 34.
The length of the end clearance is increased to accommodate between
its cutting faces 38 and 39 a ring section 310 having a
cross-section similar to that of the metallic rings 35 but of a
plastic material, preferably, polytetrafluoroethylene (Teflon).
The sector 310 is placed in the cold state without clearance
between the cutting faces 38 and 39 in such a way that, due to the
effect from the extension force of the hot dilation of ring 35 and
of sector 310, and from the gas pressure on the inner face of the
ring and the sector, both of these members are applied against the
cylinder, thereby to ensure cooperatively the closing off of the
gas passage between the cutting seal of the metallic ring 35 and
the cylinder.
The length of sector 310 must be sufficient for its elasticity
which is in the order of 4% of its length, for Teflon, to be higher
or equal to the sum of the dilation of the ring 35 and the sector
310 to prevent said sector from undergoing permanent reduction of
its length.
FIG. 4 shows a modified embodiment 42 of the compression ring 12,
in a partial cross-section of the piston 1 in its cylinder 44; the
compression ring 42 is composed of three thin elements 45, 46, 411
disposed with clearance 47 in the groove of piston 41. This
clearance 47 is limited to the minimum necessary for ensuring the
freedom of movement of the three thin elements as well as access of
the pressure from the combustion or compression chamber through the
clearance 47 on the top and on the inner cylindrical face of
compression ring 42.
FIGS. 5 through 7 separately show a planar view of each of these
three elements of compression ring 42 which are two thin cut and
joined rings 45, 55 and 411, 611 (thickness of about 0.7 mm) made
of elastic metal, for example, cast iron or steel, on the one hand
and on the other hand, one thin cut ring 46, 76 (thickness of about
0.5 mm) of a relatively plastic material such as annealed copper or
polytetrafluoroethylene (Teflon); the plastic ring 46, 76 is always
disposed between the central elastic ring 45, 55 and the groove
face of the piston which is on the side of the crankcase.
The rings 45, 55 and 411, 611 have in the free position a diameter
larger than that of the cylinder to exert an expansion force
against the cylinder and their end clearance, as distinguished from
the embodiment of FIGS. 1 and 2, is just that required to
accommodate hot dilation thereof when mounted on their piston in
the cylinder. The plastic ring 46, 76 in free state has
approximately the dimension of the cylinder and its clearance of
cutting 715 is substantially nil in the cold state so that under
the combined effect from thermal dilation and pressure acting
through the clearance 47 of the compression ring on its inner
cylindrical surface, the ring 46, 76 as well as rings 45, 55 and
411, 611, are applied against the cylinder, the more so because the
pressures in the combustion or compression chamber are higher.
In this form of embodiment, in order to be able to close off the
passage of gas along the cylinder through the cutting clearance,
one has to prevent the rings 45, 55 and 411, 611 from rotating one
relative to the other to avoid superposition of their cuttings, but
without clamping so that each one is free to move in its plane and
apply itself against the cylinder without any stress received from
the other or from the piston.
FIG. 8 is a cross-section along line A--A of ring 55 which shows an
appropriate relative retention means, i.e. providing on the lower
ring 45, 55, 85, 95 (FIG. 9) a lug 512, 812, 912 (FIG. 9) slightly
lower than the thickness of the upper ring 411, 611, 1011 (FIG.
10). In said upper ring there is formed a lodging to receive the
lug 512, 812, 912 with sufficient clearance for not clamping both
rings 45 and 411, 55 and 611, 95 and 1011 (FIG. 10). An appropriate
example of such lodging consists of two notches 613, and 614, 1013
and 1014 (FIG. 10); this position of the notches is advantageous
because it permits by mounting first the ring 45, 55, 95 in the
piston groove to mount thereafter the ring 411, 611, 1011 by
aligning its cutting opposite the lug 512, 912.
FIGS. 9 and 10 are planar views of an alternative embodiment of
rings 45 and 411. On rings 95 and 1011 as described above there are
also formed the lug 912 and notches 1013 and 1014, but supplemental
notches 916 and 1016 distributed on the inner periphery of each
ring have been added thereto.
The reasons for the presence of said additional notches and the
role thereof are the following:
Substantial width of a thin cut ring is such as to make it
difficult to obtain a sufficient radial elasticity to make a
lightweight and well distributed contact between the outer edge of
the thin ring and the cylinder. Due to the notches 916 and 1016, it
is possible both to preserve the width of the thin ring as required
for keeping it properly in the piston groove, and recover the
radial elasticity which is lacking in a wide thin ring.
Moreover, it is known that for manufacturing piston rings of cast
iron or steel having a normal thickness, it is necessary to have
recourse to variations in the circular form and in the width of the
piston ring to obtain proper distribution of the extension effort
on all the periphery of the piston rings contacting the cylinder,
avoiding in particular the stiffness of the portions adjacent the
ends. The number and location of said notches permit to influence
such distribution with little expense, for example, by regularly
distributing the notches in the sector RR as shown on FIG. 10 which
is opposed to the ends and by closer spacing near the ends.
Therefore, with thin rings of elastic metal formed with notches 916
and 1016 properly placed and distributed, there can be obtained
thin rings having new properties as follows:
elasticity, suppleness and configuration permitting lightweight
equally distributed contact on the whole periphery thereof between
the rings and the cylinder.
FIGS. 11 and 12 are perspective views of two embodiments 113 and
123 of the oil ring. It comprises a single piece of spring steel
consisting of a frusto-conical crown of very thin elastic blades
1117, 1217, for example of a thickness of 0.12 to 0.2 mm. Such
blades are separated from one another on the side of the larger
base of the frusto-conical crown and connected to one another on
the side of the smaller base of said crown, for example, through a
flat washer 1118 or a cylinder 1218.
The metal of said oil ring is submitted to a heat treatment
conferring optimum elasticity thereto either in the state of raw
material or during manufacture. The ends of the elastic blades
1117, 1217 will be lapped or honed in operating configuration
before mounting thereof. They will have a very narrow circular
contacting surface, for example, of 0.10 to 0.20 mm. of width, with
the cylinder and they can be hardened by localized complementary
treatment so as to form a contacting narrow surface of high
hardness with the cylinder thereby to increase wear protection
thereof. Such protection already results from the fact that the
blades constituting such contacting narrow surface are applied
against the cylinder with a very small force as explained
hereinafter.
FIGS. 13 and 14 are fragmentary cross-sectional views of a piston
131 or 141 mounted in its cylinder 134 or 144 and carrying at 133
an oil ring of FIG. 11 and at 143 an oil ring of FIG. 14.
The oil ring 133 is held in a groove 1320 of piston 131 by its
portion constituting a flat washer 1118, 1318 with minimum
clearance 1321. An annular spacer 1322 is used as needed to give
groove 1320 an easily produced width greater than the thickness of
the washer 1118, 1318 which may be, for example, 0.12 to 0.2 mm.
Said annular spacer 1322 is shown in FIG. 15 at 1522. It includes
if necessary a cutting 1523 to permit the mounting thereof; its
outer diameter is smaller than that of the piston since its purpose
is not to bear against the cylinder, and in the resting position,
its ends 1523 join; its thickness is shown at 1524 and will be
described below with respect to FIG. 20; it can be made of metal,
preferably, light metal, or better of plastics material for example
polytetrafluoroethylene (Teflon) or of elastics material without
cutting for example fluorated elastomer (Viton); in these latter
two cases, it acts not only as an annular spacer but also as an
annular seal.
The oil ring 143 is held on the piston 141 by its cylindrical
portion 1218, 1418 by glueing (by anaerobic resins or
cyanoacrylates, for example) in a cylindrical recess 1425 formed in
the piston. Between blades 1317 or 1417 and piston 131 or 141 there
can be formed in the piston an annular chamber 1326 or 1426 the
purpose of which is collecting oil scraped off by blades 1317 or
1417 in the downward strokes of the piston.
Return of such oil to the crankcase can be effected by the
following means used as required together or separately:
during the upward strokes of the piston:
a frusto-conical form 1327 connects chamber 1326 and the top of the
skirt 1328 of the piston; such form makes an angle with the wall of
the cylinder favoring dynamic drive of oil, for example, 7.degree.,
and causes return of oil to the crankcase through the clearance
between the piston and the cylinder.
a row of radial holes 1429 oriented downwardly of the piston and
communicating the bottom portion of the annular chamber 1426 with
the center of the piston produces through its orientation a dynamic
effect driving oil to the center of the piston. (Optionally,
similar holes could be provided to communicate with annular chamber
1326)
during the downward strokes of the piston:
a series of radial holes 1330 perpendicular to the axis of the
piston, or of holes 1431 oriented toward the head of the piston,
and communicating the top portion of the annular chamber 1326 or
1426 with the center of the piston drives oil to the center of the
piston, holes 1431 adding by their orientation a dynamic effect
thereto.
FIGS. 16 and 17 are radial and sectional views in the free position
of the oil ring 113, 133 of FIGS. 11 and 13 with slits 1632 between
the blades 1617 perpendicular to the radial plane of the oil
ring.
FIGS. 18 and 19 represent in the same manner an alternative
embodiment of the same oil ring comprising slits 1833 between
blades 1817 inclined in respect to the radial plane of the oil
ring. Due to the contacting differences between the blades and the
cylinder during the downward strokes of scraping and the upward
stroke of recycling, said inclined slits rotate the oil ring which
favors perfect conforming of the oil ring within the cylinder and
thus the efficiency thereof.
When the piston is mounted in the cylinder, the elastic blades 1317
and 1417 are contracted by the cylinder; they make with its wall an
angle .alpha. (FIGS. 13 and 14) and both faces 1119 and 1219 of the
cutting of the oil ring abut against each other. In this position,
due to their construction and except for very small clearances as
required for the operation, i.e. mainly, thermal expansions or
deformations and for lubrication, the blades 1317 and 1417 are
joined as represented on FIGS. 11 and 12 which show them connected
as they are in the cylinder. For example, with a cylinder of 80
mm., the total amount of the very small clearance between the
blades can be 0.2 to 0.4 mm. Since the number of blades is about 48
with this diameter, the clearance between blades being positioned
in the cylinder is 0.004 to 0.008 mm., i.e. 4 to 8 microns. The
very small value of such clearance involves construction of the
blade as substantially "lateral jointive blades". These clearances
can vary while remaining very small to cope with the operational
and lubrication requirements.
The edge of the crankcase side of said jointive blades which is in
the scraping position in the downward strokes and in the recycling
position in the upward strokes has a continuous circular narrow
contacting surface with the cylinder. In the free position outside
the cylinder, the ends 1119 and 1219 are preferably closed from
construction to facilitate their positioning on the piston, before
the mounting thereof in the cylinder, but the elastic blades 1117
and 1217 are opened, i.e. their outer diameter is larger and they
are no longer contacting; they present spaces 1632 and 1833
therebetween and form with the axis of the oil ring which is
parallel to the wall of the cylinder when the piston is mounted an
angle .beta. which is larger than angle .alpha.. The difference
between angle .beta. and .alpha. produces the elastic force which
applies each blade against the cylinder when the oil ring is
mounted within the cylinder.
The variation of the difference between these two angles and that
of the thickness of the elastic blades permit during fabrication
adjustment as desired in the elastic pressure supplied by each
blade being applied on the cylinder. The angle .alpha. of blades
1317 and 1417 with the wall of the cylinder is very small, for
example, an angle of 7.degree., known as being favorable to the
Kingsbury effects related to the driving of oil between walls in
motion and operating as favorable to the recycling of oil during
the upward strokes of the piston as well as to the scraping during
the downward strokes.
FIG. 20 is a perspective view of the cutting in an oil ring of the
type shown in FIG. 11, a small right-angled ledge 2034 and 2035
disposed on each end of the flat washer 2018 of the oil ring being
added on each face of the cutting. The height of said ledge is at
the maximum equal to the thickness 1524 of the annular spacer or
seal 1322, 1522. Its advantage is to provide a positive abutment
for the cutting of the oil ring both ends of which are applied one
against the other in operation, said positive abutment protecting
said ends from any risk of overlapping which might occur because of
their small thickness.
FIG. 21 shows the piston ring 2113, similar to piston ring 113 of
FIG. 11 with its flat annular ring 2118 connecting the flexible
blades 2117, but it has no separation therein and the piston ring
cannot open. Therefore, it can be mounted only on a piston
comprised of at least two parts, with the connection plane of each
said two parts forming a lateral face of the groove of the oil
ring. (This is the case for the piston shown in FIGS. 5 and 6 of
French patent application No. 81.13437 filed on July 8, 1981).
The endless construction of the oil ring may spare a manufacturing
step, makes the ring better than a cut piece to handle, is very
easy to position and eliminates any risk of overlapping of both
ends in operation. While it requires a piston composed of two
parts, this arrangement may in certain cases be the best
construction.
FIG. 22 shows a piston ring 2213 similar to piston ring 113 of FIG.
11 but the annular ring 2218 is formed with inwardly open radial
cuttings 2236 extending the full or only part of the width or ring
2218.
Such radial cuttings are distributed in a number at most equal to
the number of blades 2217 all around the flat ring 2218 and each
cutting is disposed opposite a blade 2217 and at equal distance
from both cuttings delimiting such blade so as to provide the
largest possible distance of uncut material between the bottoms of
each radial cutting and those of the separation cuttings of the
blades. The radial cuttings 2236 can be in a smaller number than
that of the blades, in that case, they are distributed as regularly
as possible on the periphery of the piston ring. The radial
cuttings permit the piston ring to open and be positioned easily
while avoiding any deformation in a very narrow groove.
According to a certificate of addition to the main patent filed in
France on Jan. 15, 1982 under No. 82/00625 an alternate form of
embodiment of the compression piston rings of FIGS. 2 and 4 above
consists of a flat ring that may present any known section of
compression piston ring and a thin section of elastic metal e.g.
cast iron or steel, characterized in that it comprises at least one
element, the periphery of which is made by construction to the form
and dimension of the cylinder, said ring having at least one
cutting contacting the cylinder and submitted to the action of a
micro-spring of a thickness not in excess of that of the ring, said
micro-spring(s) housed in the groove of the ring slightly
increase(s) the diameter in the free condition of said ring, so
that when the ring is in the cylinder the cutting(s) contacting the
cylinder present(s) the required clearance for thermal extension of
the ring, on the one hand, and on the other hand, the
micro-spring(s) is (are) compressed and exert(s) upon the ring an
opening force parallel to its circumference and which is
transmitted to the whole of the latter, by producing a force
applying it to the cylinder, such force being identical at any
point on the circumference.
The good contact distribution and the great precision of such
piston ring in its application to the cylinder as well as the
regularity of the elastic force applied to the cylinder permit to
ensure very efficient tightness and reduction of the application
pressure of the ring against the cylinder to a very low level, and
the less thick the ring, the lower the pressure.
FIG. 23 shows an example of compression ring according to the
invention consisting of a ring 2337 without through cutting
clearances made of elastic metal. Its cross-section is regular on
all its periphery; it can be of any known compression ring shape.
Preferably, such compression ring will be made of spring steel and
its thickness will be small, for example, 0.60 mm. with a
compression ring of 80 mm. of diameter.
Such ring may be made of a single part without through cutting if
it is mounted to a piston made of multiple parts (as in the case of
FIG. 7 of the above-mentioned French Pat. No. 81.13437 of July 8,
1981). Otherwise, it may comprise one or more cuttings. FIG. 23
shows such ring without cutting but there are three dotted lines
2338 which represent three possible cuttings, and in this case, the
ring would be composed of three sectors. The faces of each cutting
are joined when the ring is mounted so that the numbers of cuttings
and sectors, i.e., a cutting and two sectors at the minimum have no
influence at least theoretically upon the ring behavior.
Such ring has at least a plurality of partial alternate radial
cuttings; FIG. 23 represents three micro-springs formed by such
cuttings 2339.
FIG. 24 shows a sector 2440 including partial alternate radial
micro-spring cuttings 2439 and FIG. 25 shows in enlarged detail one
of said partial alternate radial micro-spring cuttings each of
which comprises at least one partial outwardly open cutting 2541
and a partial inwardly open cutting 2542, which produce
therebetween an elastic deformable tongue 2543 which is used as a
spring. Each group could comprise a large number of partial
alternate cuttings open outwardly and inwardly.
When the ring is mounted in the cylinder, those partial cuttings,
in particular, the outer cuttings 2541 are very narrow because they
must together be equal to the clearance required for thermal
expansion of the ring. For a ring of for example 80 mm., such
clearance is in the order of 0.40 mm. If it comprises three sectors
2440 each having a micro-spring 2439, the width of each partial
cutting 2541 positioned in the cylinder would be about 0.13 mm.
Assuming that each alternate cutting is realized with a width of
for example 0.50 mm., the length of the circumference of the ring
in the free state in excess of that of the cylinder would be:
3.times.0.50-3.times.0.13=1.11 mm., which would correspond to a
diameter in excess of that of the cylinder of 1.11/=0.353 mm.
For mounting the ring in the cylinder, the cuttings of each sector
will be jointive, abutting one against the other, and each
micro-spring will undergo compression urging increase of the ring
diameter, thereby to apply it against the cylinder. Such
enforcement will be distributed regularly on the contour of the
ring, because such contour will exactly follow the cylinder wall
since it was made to its form and size, on the one hand, and on the
other hand, because the micro-springs will exert his (their) bias
in the circumferential direction, thereby transmitting exactly the
same effort to all the points on the circumference of the ring,
particularly with at least three micro-springs regularly
disposed.
For a given thickness of the ring, the widths B and D in FIG. 25
formed between the bottom of the cuttings and the outer and inner
edges of the ring, the width C of each elastic tongue 2543 on one
hand and on another hand the width of the cuttings 2541 and 2542
which would increase the diameter of the free piston ring
constitute means for adjusting the characteristics of each
micro-spring 2339, 2439 in order to obtain the most accurate
contact pressure between ring and cylinder as required and to cope
with the effects of wear. Preferably, the bottoms of the partial
cuttings 2541, 2542 are rounded up to prevent initiating breakages
by metal fatigue about said cutting bottoms.
The periphery of such piston ring is obtained by any known forming
means such as by rolling, machining, grinding to a diameter very
close, or even exactly equal to that of the cylinder.
If the ring is in a single piece and has no through cutting therein
it will be necessary to make it to a diameter slightly higher than
that of the cylinder to obtain, in the cylinder, a clearance
corresponding to thermal expansion after compression of the
micro-springs.
If the ring is composed of several sectors, each sector in the free
state is slightly longer 2443 than that fraction of circumference
of the cylinder which it must occupy, in order to ensure
compression if its micro-springs 2439 and to reduce the width of
its partial cuttings 2541 to the clearance required for thermal
expansion of the ring. Such elongation of the section will be
particularly easy with rings made by rolling continuously steel
band. As a matter of fact, such process permits to obtain a roll of
jointive windings which can be ground outwardly to the exact size
of the cylinder, and sectors of any lengths can be cut in this
roll.
Finally, when for example in large cylinders the ring is thick
enough and the ring itself includes at least one through cutting
therein, following a variant of the invention, the micro-springs of
the type shown in FIG. 25 may be replaced as illustrated in FIG. 26
by one or more coiled springs 2646 housed in holes 2647 made in the
faces of the cuttings.
All the above-mentioned exemplifying dimensions for thicknesses of
materials, contacting width between blades and cylinder, various
clearances or other correspond to parts for a cylinder diameter in
the order of 80 mm.
These various dimensions may vary depending on the diameter of
cylinder, but remain in the proportion determined by the
above-mentioned numerical examples.
The operation and advantages of this new assembly cylinder,
lightweight piston and piston rings are the following:
The compression ring, FIGS. 2 and 4, comprises at least one thin
elastic metallic ring the ends of which are provided with closing
means for sealing off the gas passage along the cylinder and
associated with a further seal of Teflon, for example. Due to the
closing of the ring ends passage, and to the assistance of the
seal, the compression ring produces very high tightness against gas
passage, with reduced frictional efforts on the cylinder because
the compression force of thin rings is much smaller than that of
the usual thicker compression rings.
As to the compression ring in FIGS. 23, 24 and 25, it will provide
new results as compared to the known rings:
its contact with the cylinder is the best possible since it is
formed, machined or ground to a shape and size very close, if not
exactly equal, to those of the cylinder.
the application force of its periphery on the cylinder is the same
in all points. For these two reasons, this force is much lower than
that of any other ring. Moreover, it only results from the reaction
of micro-springs 2339, 2439, 2639 which can only develop very low
forces.
finally in the case of micro-springs 2339, 2439, it has no
clearance from its total cutting as its total cutting(s) 2338 if
there is any is(are) jointive and the cutting clearance on the
periphery of the ring which is required for thermal expansions is
divided by the number of the micro-springs 2439, which laminate the
blow-by through division into as many passages.
Thus, such ring is much tighter than any known rings with much
smaller friction and wear. Moreover, such ring is very well adapted
to the use of a groove seal made of Teflon whether it be without
any cutting if mounted to a dismountable piston or with cutting as
described in relation to the other rings, thereby still increasing
efficiency against gas passages.
Furthermore, said ring has a great circumferential flexibility by
increasing the number of groups of partial alternate radial
cuttings, which results in significant advantage with engines
having cylinders submitted to large deformations in operation.
Finally, its manufacturing from thin steel realized by rolling as
explained above is much more economical than the production of the
presently used conventional rings.
On the other hand, it is known that a gas passage tight compression
ring has the disadvantage of producing an oil pumping effect to the
top portion of the cylinder. The cooperation with the oil ring of
very high efficiency as seen hereinafter, remedies this
disadvantage.
It is also known that the steadiness in service of the seal of
plastics material (in particular, Teflon) is excellent; it may last
as long as the engine save for the attack of its outer edge by the
asperities of the cylinder which are required in the present state
of the technology to provide oil reserves on the walls of the
cylinder to avoid scuffing.
However, the very high reduction of the gas passage and of the
friction of the compression ring by eliminating the dragging along
of abrasive combustion residues, the hot points of the compression
ring and the burning of oil, on the cylinder and about the
compression ring, create new lubrication conditions which lead to
two new advantages:
prolongation of the contact between the piston and the cylinder up
to the piston head, normally limited to the piston jacket below the
oil ring, on the one hand, and on the other hand,
utilization of a very high polishing level for the inner surfaces
of the cylinders.
These two measures reduce friction, improve thermal exchange
between cylinder and piston and in addition to the fact that the
piston may be at a lower level by having only two ring segments,
they permit reduction of its height and therefore a substantial
reduction of its weight. Moreover, they alleviate the lateral wear
of the seal of plastic material (in particular, Teflon).
As regards the operation of the oil ring, its elastic blades have
only a contacting circular narrow surface with the cylinder under
very light pressure and are put in an ideal position both to scrape
oil in the downward strokes and recycle it in the upward strokes;
therefore they ensure at the highest level possible the control of
the oil climbing toward the combustion chamber and the reduction of
the very high friction of usual oil rings which effect scraping
through high pressure from lips having not a contacting narrow
surface with the cylinder but a contacting larger surface
therewith, and working in a perpendicular position against the
cylinder which is unfavorable to the scraping and recycling since
in one stroke out of two, the upward stroke, oil rings
perpendicular to the cylinder scrape and return oil in the wrong
direction, on the side opposite to the crankcase.
Thus, the new assembly positively combines by a new cooperation of
its various elements:
the reduction to a negligible level or the suppression, of passage
of gas between piston and cylinder;
more effective control of the oil climbings;
the reduction of most of the friction and wear between pistons and
cylinders;
the lightening of the piston and its piston rings.
This combination thereby reduces expenditure of energy, oil,
mechanical wear and maintenance.
Still further advantages result therefrom, among them, in
particular, better cold starting by improvement of the compression,
especially with Diesel engines, and the reduction of pollution by
diminishing the clearance volume of air and fuel between piston,
piston rings and cylinder.
Finally, it must be noted that the separate utilization of the
compression ring and the oil ring as described in this application
is within the scope of this invention, since although such
utilization will not produce all the effects from the above
mentioned combination, each of those elements used separately
brings about its own advantages, in particular:
as regards the compression ring: high tightness against blow-by,
reduction of friction, diminution of wear, lightening of the
compression ring, better performance, improved duration of the
elements and saving of energy;
as regards the oil ring: simple effective scraping of oil, very
efficient in the downward strokes by returning oil to the crankcase
and simple effective recycling of the oil film remaining on the
cylinder, very efficient in the upward strokes bypassing oil into
the crankcase circuit, reduction of the friction on the cylinder to
a very small fraction of the friction produced by all the other oil
rings, reduction of wear, lightening of the oil ring, better
performance, improved duration of the elements and saving of
energy.
The two main elements of the invention have therefore an
individuality which remains separately useful but only their
combined cooperation produces all the advantages of the
invention.
Specifically:
the compression ring, if used separately from an oil ring having a
very effective oil control, cannot eliminate the oil pumping effect
already mentioned above which causes excessive oil consumption,
which is very difficult, if not impossible, to reduce sufficiently
and safely enough in mass production.
if the oil ring is used separately from the compression ring:
it is exposed to gas passage from the usual compression rings and
thus, receives together with such gases abrasive combustion
residues produced and driven thereby, which is a cause of wear of
its contacting narrow surface with the cylinder, on the one hand,
and
on the other hand, it is bound to operate in such a cylinder having
the usual rugosity levels instead of using a cylinder having a very
high level of polishing.
These two conditions are detrimental to the proper preservation
without wear of the narrow circumferential bearing of the elastic
blades of the oil ring against the cylinder.
* * * * *