Piston ring construction

The disclosure embraces a piston ring construction particularly an oil control ring construction comprising a parted oil control ring or rings and a parted compressible spacer-expander ring or spring member, the spacer-expander member configurated with strut portions, pairs of the strut portions having their end regions integrally joined by connectors, the connectors being formed with inwardly extending portions, the spacer-expander member being arranged to exert substantially uniform outward radial pressure against one or more oil control rings, the spacer-expander member being adapted to accommodate a latch member for bridging the ends of the member.

The invention relates to a piston ring construction particularly for use as 
an oil control ring construction for reciprocating piston engines of the 
heavy duty types and diesel types, the invention particularly embracing a 
spacer-expander ring construction for use with cast iron oil control or 
oil sealing rings. 
Several types of compressible spacer-expanders have been used in 
association with cast iron rings but such spacer-expanders have 
deficiencies which render assembly difficult or which impair the 
efficiency of the oil control sealing rings with which the 
spacer-expanders are used. There are three general types of 
spacer-expanders that have been heretofore used with cast iron rings, such 
types being usually referred to as the equalizer type, the helical 
compression spring type and an expander type of U-shaped cross section. 
The equalizer type of spacer-expander comprises a strip of metal formed 
into undulated or wavy configuration wherein the undulations are in axial 
directions of the spacer-expander. One of the difficulties in the use of 
the equalizer type of spacer-expander is the tendency for the ends to 
overlap at installation. When this occurs without being detected, there 
can be severe impairment of the operation of the spacer-expander. For 
example, the spacer-expander does not exert radial outward pressures on 
the oil control sealing ring and hence the sealing ring does not perform 
its function of controlling oil. 
In some instances there is insufficient space in the piston groove for the 
overlapped spring and the cast iron ring resulting in the spring becoming 
crushed or broken and the cast iron ring and expander spring locked in 
place exerting pressure on the cylindrical wall which can cause severe 
scoring of the cylindrical wall. The equalizer type has substantially no 
resilience in radial directions. 
If the equalizer type of expander is not coiled to a true circle, it may 
promote uneven pressures and an uneven wear pattern against the inside 
diameter of the cast iron ring. Such uneven pressures are transmitted to 
the outside diameter of the cast iron oil ring causing uneven wear and 
hence ineffective oil control. As the equalizer type is undulated in an 
axial direction of the ring, it is quite flexible in such direction. 
When it is compressed there is a tendency for the expander to contact the 
side of the groove in the piston setting up excessive friction impairing 
the performance of the expander to exert proper pressure on the cast iron 
oil control ring. Furthermore, a latch member cannot be used at the ends 
of the ring because of the undulated configuration. 
Spacer-expanders of the coil spring type have been used but such 
spacer-expanders are unsatisfactory in several respects. The coil spring 
tends to score the inside surface of the oil control ring and this impairs 
the radial outward pressure of the spring against the oil control ring. 
Coil spring expanders are fashioned with closely spaced convolutions which 
tend to inhibit ventilation through vent openings in the control ring or 
vents in the ring groove opening into the interior of the piston. 
The spacer-expander of U-shaped cross section is usable with a single cast 
iron oil control ring but it is not readily adaptable for use with two oil 
control rings where it is desired to resiliently bias both rings outwardly 
with uniform pressures against the cylinder wall. 
The present invention embraces the provision of a piston ring construction 
embodying a parted circumferential spacer-expander or spring member 
associated with a piston sealing ring or rings, the spacer-expander being 
fashioned of a strip of thin metal and configurated to provide radially 
acting biasing pressures against a piston sealing ring or rings so that a 
substantially uniform engagement of the piston rings with the cylindrical 
wall is attained to provide a highly efficient and effective oil control 
ring construction. 
The invention has for an object the provision of a piston ring construction 
embodying a parted spacer-expander or spring member having inwardly bent 
portions providing radial resiliency for biasing a piston ring or rings 
into effective sealing engagement with a cylinder wall wherein the outward 
biasing pressures are substantially uniform throughout the circumference 
of the spacer-expander and wherein the inwardly bent portions provide a 
construction adapted to receive or accommodate a latch member bridging the 
ends of the spacer-expander member to facilitate installation in the ring 
groove in a piston. 
Another object of the invention resides in a piston ring construction 
wherein a parted circumferential spacer-expander or spring is fashioned 
with portions disposed at acute angles with respect to the axis of the 
ring construction providing effective outward radial biasing pressures 
against two oil control rings which are substantially uniform throughout 
the circumference of the ring construction. 
Another object of the invention resides in a piston ring construction 
embodying a parted circumferential spacer-expander or spring means 
fashioned of thin strip metal or metal ribbon formed to provide strut 
sections joined at their end regions with connectors, the connectors 
having inwardly bent portions, the strut sections and the inwardly bent 
portions being arranged to provide ample vent spaces throughout the 
circumference of the spacer-expander or spring means. 
Another object of the invention is the provision of a piston ring 
construction embodying a parted circumferential spacer-expander spring 
member configurated with strut sections and connector sections, the 
connector sections having inwardly bent portions, the strut sections and 
the inwardly bent portions providing radially outwardly biasing pressures 
against two sealing rings whereby outwardly biasing pressures are 
substantially uniform throughout the circumference of the spacer-expander 
spring member, the spaces between the strut sections and the inwardly bent 
portions accommodating a latch member bridging the ends of the 
spacer-expander spring member.

Referring to the drawings and initially to FIGS. 1 and 2, there is 
illustrated in cross section a cylindrical skirt portion of a 
reciprocating engine piston 10 and a portion of a cylinder 12 having a 
cylindrical bore 14 accommodating the piston 10. The piston 10 is equipped 
with conventional compression rings (not shown) disposed in conventional 
grooves in the piston. 
The piston 10 is provided with a circumferential ring groove 16 which 
accommodates an oil control ring construction and a form of 
spacer-expander or spring member of the invention. The ring groove 16 is 
defined by an upper wall 18, a lower wall 20 in parallelism therewith and 
a cylindrical back or bottom wall 22. Oil drainage vent openings or slots 
24 extend from the back wall 22 to the interior of the skirt portion of 
the piston for accommodating flow of oil from the ring groove 16 to the 
interior of the piston. 
The oil control ring assembly 26, as shown in FIGS. 1 and 2, is of a 
three-piece construction comprising a parted spacer-expander ring or 
spring member 30 and two oil control or sealing rings, viz. upper and 
lower parted oil control rings or ring segments 32 and 34. The rings or 
ring segments 32 and 34 are preferably fashioned of cast iron but may be 
made of other metals. 
The sealing rings 32 and 34 are respectively configurated to provide 
portions 38 and 39 of restricted area for sliding engagement or contact 
with the cylindrical surface of the cylinder bore 14. The lower regions of 
each of the rings 32 and 34 are provided with circumferentially-spaced 
radially extending vent openings or grooves 35 and 36 for venting oil to 
the slots 24 in the piston skirt. 
Disposed between the inner surfaces 40 and 42 of the respective sealing 
rings 32 and 34 and the cylindrical back or bottom wall 22 of the ring 
groove 16 is the spacer-expander ring or spring member 30 as shown in FIG. 
2. The spacer-expander ring 30 and its method of fabrication are more 
specifically illustrated in FIGS. 3 and 4. 
In the embodiment illustrated in FIGS. 1 through 4, the spacer-expander 
ring or spring member 30 includes vertically-arranged struts 46, pairs of 
the struts being joined at their respective end regions by connectors or 
connecting portions 48 and 49 which are bent as at 50 and 51 providing 
inwardly bent portions 53 and 54. As shown in FIGS. 2 and 3, the upper 
circumferentially-spaced inwardly extending portions 53 are arranged at 
acute angles with respect to the vertical struts 46. 
The portions or projections 54 of the lower group are bent inwardly toward 
the other bent portions and are arranged at acute angles with respect to 
the struts 46. The ends or terminals of the inwardly bent portions or 
projections 53 and 54 do not overlap but are spaced apart as indicated at 
56 in FIG. 2. The bent portions are in spaced relation with the struts 46 
as shown in FIGS. 3 and 4. 
While the degree of acute angularity of the inwardly extending portions 53 
and 54 with respect to the struts 46 may be varied depending upon 
particular wedging or biasing characteristics desired, it is found that 
the angularity indicated at "A" of the projections with respect to the 
vertical struts 46 should be between 5.degree. and 25.degree. and 
preferably of an angularity of about 15.degree.. 
The inner surfaces 40 and 42 of the respective oil control rings 32 and 34 
are preferably of reciprocal angularity substantially the same as or 
contiguous with the angularity of the projections or portions 53 and 54, 
as shown in FIG. 2. The cross sectional configuration of the 
spacer-expander ring or spring member 30 provides for substantially 
uniform outward radial pressures against the oil control rings 32 and 34 
throughout their circumferences. 
As illustrated in FIG. 3, the spaces between the struts 46 and the angular 
portions 53 and 54 at the parting region of the spacer-expander 
accommodate a latch member 60. The latch or connecting member may be 
fashioned of a strip of plastic such as nylon or it may be made of thin 
metal. One end region of the latch member, as shown in FIG. 3, extends 
into one end of the parted expander and is anchored in a conventional 
manner in the said one end of the expander. 
The latch member 60 extends into spaces between the vertical struts 46 and 
the angular portions or projections 53 and 54 at the other end of the 
expander and is slidable therein and bridges the ends of the parted ring 
to facilitate installation in the piston ring groove 16. 
An important feature of applicant's spacer-expander construction is that it 
accommodates a latch member without any impairment of the radially outward 
expansive characteristics of the spacer-expander spring. The angularity of 
the portions 53 and 54 exert biasing forces to urge the respective oil 
control rings 32 and 34 toward the upper and lower walls 18 and 20 of the 
groove 16 in the piston. 
FIG. 4 shows the configuration of a stamped, die cut or perforated blank 62 
illustrating a method of forming the spacer-expander 30 of the 
construction shown in FIGS. 1 through 3. A strip or ribbon of thin metal 
is die cut or perforated to form the circumferentially spaced pairs of 
struts 46 integrally joined by connectors 48 and 49. The connectors are 
bent to the configuration shown at the left portion of FIG. 4 and in FIGS. 
2 and 3, forming the upper row of projections 53 and the lower row of 
projections 54. Thus, it will be apparent that the formation of the 
spacer-expander 30 requires a minimum of processing steps in attaining its 
completed configuration. 
The oil control ring and spacer-expander construction 30, shown in FIGS. 1 
through 3, provides for substantially uniform outwardly directed radial 
pressures of the spacer-expander ring 30 against the parted oil control 
rings or ring segments 32 and 34 to establish and maintain an effective 
sealing engagement of the peripheral surfaces of the oil control rings 
with the cylinder bore surface 14. The configuration of the 
spacer-expander 30 provides substantial open areas for venting oil to the 
vents 24 in the piston skirt. 
FIGS. 5 and 6 illustrate a modified form of spacer-expander construction of 
the invention. The spacer-expander oil control ring construction 66 
includes a parted spacer-expander member or spring 68 and upper and lower 
cast iron oil control rings or ring segments 32' and 34' contained within 
a ring groove 16' in a piston 10', the rings 32' and 34' being in 
engagement with the cylinder bore surface 14'. 
In the arrangement shown in FIGS. 5 and 6, the struts 70 of the 
spacer-expander 68 are arranged for engagement with the oil control rings 
32' and 34' and the inwardly extending portions or projections 72 and 73 
are in vertical relation as shown in FIG. 5. The struts 70 comprise upper 
portions 75 and lower portions 76 arranged at acute angles with respect to 
the inwardly extending portions 72 and 73, each pair of the angular 
portions 75 and 76 being integrally joined as single struts, as 
particularly shown in FIG. 6. 
The exterior surfaces of portions or projections 75 of the upper row are in 
contiguous engagement with the angular surfaces 40' of the upper oil 
control ring 32', and projections or portions 76 of the lower row in 
contiguous engagement with the angular surfaces 42' of the lower oil 
control ring 34'. The inwardly extending portions or projections 72 and 73 
are not in overlapping relation, the ends being spaced as indicated at 78. 
In this form, each of the struts 70 is fashioned with two acute angular 
connected portions 75 and 76 which are in engagement respectively with the 
oil control rings 32' and 34', the inwardly extending portions or 
projections 72 and 73 being in substantial parallelism with the bottom 
wall 22' of the ring groove 16'. The expansive characteristics of the 
spacer-expander ring 68 bias the circumferential exterior surfaces 38' and 
39' of the cast iron oil control rings 32' and 34' into engagement with 
the surface of the cylinder bore 14'. 
The construction shown in FIGS. 5 and 6 provides spaces between the angular 
portions of the struts 70 and the inwardly extending portions or 
projections 72 and 73 to accommodate a latch member of the character 
illustrated at 60 in FIG. 3 for bridging the ends of the parted 
spacer-expander 68. The construction shown in FIGS. 5 and 6 functions in a 
manner similar to the functioning of the construction shown in FIGS. 2 and 
3. 
FIGS. 7 and 8 illustrate a modified form of spacer-expander or spring 
especially adapted for use with a single cast iron oil control ring 80 
disposed in a ring groove 16" in a piston 10", the ring 80 having a 
restricted peripheral region 82 for engagement with the surface of a 
cylindrical bore 14" of a cylinder 12". Disposed between the ring 80 and 
the base or bottom wall 22" of the ring groove is a spacer-expander or 
spring 84, a portion of the spacer-expander or spring 84 illustrated in 
FIG. 8. The method of configurating the spacer-expander 84 is illustrated 
in FIG. 9. 
The spacer-expander 84 comprises vertical struts 86, pairs of the struts 
being integrally joined at their upper ends by connectors 87 and the lower 
ends of the struts integrally joined by connectors 88. In this form the 
struts 86 are parallel with the axis of the piston. The connectors 87 have 
portions or projections 90 bent inwardly in parallelism with the struts 
86. The connectors 88 have portions or projections 92 bent inwardly in 
parallelism with the struts 86, the portions 92 being in substantially 
vertical alignment circumferentially with the inwardly extending portions 
90. 
The portions 90 of the upper row and the portions 92 of the lower row do 
not overlap but are separated by spaces, one of which is indicated at 94 
in FIG. 7. The inwardly extending portions 90 and 92 are spaced from the 
strut portions 86, as shown in FIG. 7, to accommodate a latch member 60", 
a portion of which is illustrated in FIG. 8. Through the arrangement 
illustrated in FIGS. 7 and 8, the spacer-expander provides 
circumferentially uniform outward radial pressures against the oil control 
ring 80 to bias the oil control ring into effective sealing engagement 
with the cylindrical bore surface 14". 
The spacer-expander construction accommodates a latch member 60" in the 
same manner as the latch member 60 is accommodated in the arrangement 
shown in FIG. 3 for bridging the parted ends of the spacer-expander or 
spring 84. The struts 86 are in contiguous engagement with the inner 
cylindrical surface 81 of the oil control ring 80 throughout the 
circumference of the spacer-expander. 
A method of fashioning the construction shown in FIG. 8 is illustrated in 
FIG. 9 wherein a strip or ribbon of metal, such as strip steel, is 
perforated or die cut to provide pairs of struts 86, the upper ends of 
which are integrally joined by connectors 87 and the lower ends integrally 
joined by connectors 88. The connectors 87 are shaped or bent to form an 
upper row of inwardly bent portions or projections 90, and the connectors 
88 shaped or bent to form a lower row of inwardly bent portions or 
projections 92. The arrangement shown in FIGS. 7 and 8 comprises a 
spacer-expander or expander spring 84 which is inexpensive to manufacture 
and which accommodates a latch member 60". 
It is apparent that, within the scope of the invention, modifications and 
different arrangements may be made other than as herein disclosed, and the 
present disclosure is illustrative merely, the invention comprehending all 
variations thereof.