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Патент USA US2130923

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Sept. 20, 1938.
2,130,923
F. JARDINE
PISTON LAND CONSTRUCTION
Filed April 16, 1936
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F'EA/VK JARED/IVE
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Patented-Sept. 20, 1938
2,130,923
UNITED‘ STATES , PATENT OFFICE 2,130,923
PISTON LAND CONSTRUCTION
Jardine, Cleveland, Ohio, assignor, by
mesne assignments, to Cleveland Trust Com
puny, Cleveland, Ohio, a corporation'of Ohio,
trustee
'
.
Application April 1a, 1936, Serial No. 74,736
18 Claims. (01. 309-10)
This invention relates to pistons for internal ring lands and the walls of the cylinder in the
combustion engines, and more particularly to an conventional piston constructions have been great
improved ring land construction for internal com
bustion engine pistons.
The conventional ‘internal combustion engine
piston combines the functions of a piston and a
7 cross head and includes a head having- a cylin
drical ?ange grooved on the outside to receive
packing rings, bosses to support the wrist pin
to join the piston tothe connectingrod, and a
skirt which has surfaces arranged to slide upon
the cylinder walls to guide the piston in its re
enough so that at the maximum operating tem
perature the excess expansion of the piston head
will not bring the lands into engagement with 5
the cylinder wall, .and also great enough to pre
vent contact between the ring lands and the cylin
der wall upon bodily movement of the piston with
in the cylinder resulting from yielding of the skirt
under the lateral thrusts to which the piston is 10
subjected during reciprocation.
-
As a result the piston is guided in the cylinder
, Pistons composed of light metal such as alumi
only by the skirt, the ring ?ange of the head
serving to carry the piston packing rings and, in
num alloys and the like for operation in cast iron
most constructions, to connect the head with the
ciprocation.
'
v
cylinders ‘have many recognized advantages in
wrist pin bosses and the skirt.
internal combustion engines. Aluminum and
other light metal alloys, however, have a sub-~
piston having a yieldable skirt to accommodate
the excess expansion of the light metal alloy it
will be apparent that the head is maintained cen
tered within the cylinder by the skirt, which is a
stantially higher coe?icient of expansion than
cast iron. Accordingly, in order to obtain skirt
bearing surfaces which will freely slide within
‘ the cylinder without binding atall temperatures .
encountered in operation, and which have a sum
ciently close lit at low operating temperatures to
prevent the piston from slapping back and forth
In the type of -
yieldable support. During the normal operation
of a conventional Otto cycle internal combustion
[engine with connecting rods, or pitmen, connect
ing the piston to the crankshaft, there are six
reversals of the direction of thrust of the piston
_ in the cylinder, it has been necessary to provide _ against the cylinder walls during each complete
some means for compensating for vthe excess cycle, or each two revolutions of the crankshaft.
One reversal occurs at each end of each stroke
thermal expansion of the piston within the cylin
and likewise reversals occur at the point in the
intake and exhaust strokes where the accelera
The most widely used constructions for‘ com
pensating for the excess thermal expansion of a tion of the piston changes to deceleration. At
light metal piston skirt have been those in which each reversal of the direction of thrust a tendency
exists for the piston head, due to its inertia, to
the skirt is made yieldable so that when the pis
ton is cold it may be fit fairly closely, at least at swing towards one side or the other of the cylin
der.
-
~
certain points, and will yield to avoid binding or , der about‘its yieldable support by the piston skirt. 35
excess friction when the piston is hot.
One of
’ these is the ‘split skirt piston in which one or
Similarly other forces exerted upon the piston
tend to cause the piston head to tilt one way or
another towards the walls of the cylinder.
’Illting of the piston head within the cylinder
successful yleldable skirt construction which has . results in excessive oil consumption“ It is uncer
heretofore been used is the T-slot piston such as tain exactly why the tilting of the piston even an
more substantially vertically extending slots are
cut through the height of the skirt. The most
' illustrated in the patent to Moore, No. 1,927,611.
In all skirted pistons it has been customary to
provide the ring flange of the piston head with
grooves within which are ?tted expansible pack
ing rings, the grooves'being separated by lands
on the ?ange. These lands of the piston‘ head
have been ?nished with a diameter such that
they do not engage the cylinder wall at any tem
perature encountered in operation, so that the
guiding function is performed by the piston skirt
extremely slight amount causes excessive oil con
sumption, but according to one theory the edges
of vthe piston packing rings which engage' the
oil ?lm upon the surfacewof the cylinder when the
head and the rings are tilted act to break the
continuity of the oil film which permits the oil
to escape from the cylinder wall and be burned
in the combustion chamber.
According to anoth'er'theory the tilting of the
packing rings creates wedge shaped spaces be
tween the bearing surfaces of the rings and the
cylinder wall which squirt oil upwardly into the
combustion chamber. It has also been suggested
The clearancesleft between the surfaces of the that when the rings are tilted their edges serve 55
and the sealing function is performed only by
the expansible packing rings mounted in the ring
grooves‘.
'
-
-
2
to scrape oil on the upward strokes and that
during the explosion the spacing of the upper edge
engagement with the cylinderzwalls at the ends
of the diameter perpendicular to the wrist pin
of the ring from the cylinder wall on one side may
axis so that such areas may move into engage
permit combustion between-the ring and the cyl
inder wall resulting in burning of small quantities
of oil. In addition when the oil ?lm is broken
excessive friction is developed between the piston
and the cylinder wall resulting in localized high
temperature which burns oil upon the bearing
ment with the cylinder wall at the end of the
lateral movement of the piston in eitherdirection
10 surfaces. Some or all of these phenomena may
occur when the piston head tilts or rocks within
permitted by the yieldable nature of the skirt.
Pistons constructed in. accordance with this
invention prevent any tilting or rocking of the
piston within the cylinder while permitting the
use of any desired construction to make the skirt
yieldable to compensate for the excess expansion
the cylinder, resulting in oil waste. It will be
of the light metal piston alloys. Oil consump
observed that if as much as one eighteen-mil
lionth of a gallon of oil is wasted or consumed
tion is reduced to aminimum without the use
of special packing rings and without excessive
friction within the cylinder. Likewise all danger
of head slap from rocking or swaying of the head
with respect to the skirt is eliminated.
15 by each piston in each cycle in an average six
cylinder automobile‘ engine, a gallon of oil will be
consumed or wasted during each thousand miles
that the automobile travels. It is therefore diffi
cult to determine exactly why tilting or cooking of
20 a piston causes excessive oil consumption, or the
exact operation by which the present invention
cures such excessive consumption.
‘
'
According to the present invention the piston
head is so constructed as to bear upon the cylin
25 der walls and prevent the head from tilting or
rocking with respect to the skirt or cylinder to‘
Further advantages relating to simplicity of
construction and economies in manufacture will
appear from thefollowing description and the
attached'drawing wherein:
'
Figure 1 is an elevation with parts in section
of a piston constructed according to my inven
tion;
vFigure 2 is a plan view looking down on'the
piston and cylinder assembly of Figure 1;
'
Figure .3 is an elevation on an enlarged scale
thereby prevent any head slap and likewise main-_
tain the cylindrical bearing surfaces of the pack ‘ of one form‘of ring land construction;
ing rings inaccurate alignmentwith the cylin
Figure 4 is a view similar to Figure 3 illustrat
30 der walls. More speci?cally the present inven
ing a modi?ed land construction;
,
.
tion provides an arrangement whereby suf?cient
bearing is obtained between the piston head and
thecylinder wall to prevent tilting of the piston
while at the same time provision is made for the
35 excess thermal expansion of light ‘metal piston
alloys so that the piston may reciprocate freely
within the cylinder at all operating temperatures
without danger of binding, scoring or excessive
friction.
"
-‘
In addition the present invention includes a
light metal alloy piston having a yieldable skirt
of any type designed for operation in an engine
cylinder composed of cast iron or the like and a
ring ?ange upon apiston head having portions
45 arranged to bear upon the cylinder walls to pre
vent tilting or rocking of the piston.
Figure 5 is a view similar to Figures 3 and 4 ‘
and illustrates a furthermodi?cation; and ~
Figure 6 is a view corresponding to Figure 2
illustrating a modi?ed land contour.
‘
Generally speaking, I have attained ‘certain ,
objects
and ' avoided
many
disadvantages
in
piston lan'd construction above referred'to by in
creasing the diameter of the piston head or land
portion across the thrust face axis, andrby main
taining the normal clearance across the piston ,
pin axis, or in some instances, actually increas-'
ing the clearance between‘ the piston head and
the cylinder wall across the wrist pin axis.
Preferably the contour of the head portion of the
piston is obtained by machining the piston head I
to provide the same with an oval cross sectional
A piston according to this invention is prefer
ably constructed with ring lands ground oval in
cross section with the major axis of the oval
50 perpendicular to the wrist pin axis and with a
clearance at the ends of the major axis such that
when the skirt yields under a lateral thrust and
the piston thereby moves laterally within the
cylinder, one end of the major axis of the,ring
55 lands comes into engagement with the cylinder
contour, wherein the major axis of the oval as at
B (Figure 2) coincides with the thrust face axis
of the piston and the minor axis of. the oval as at
C coincides with the wrist pin axis of- the piston.
The primary result of decreasing the clearance
between the piston head and the cylinder Wall
across the thrust face axis is to permit the ring
lands in that portion of the piston to‘ bear
against the cylinder wall and serve as a guide I‘
wall, thereby preventing further movement of - to prevent tilting of the piston and thereby re
, the piston head and consequent tilting within the strict the piston to a truly vertical reciprocation
cylinder. By reason of the oval contour of the ' within the cylinder.
'
ring lands the circumferential length which‘ may
60 move into engagement with the cylinder wall is
limited and the friction is thereby limited. The
ring lands may also be constructed to engage
the cylinderwall through only a part of their
height to further limit the area’ in engagement‘
65 and the friction. When the piston reaches its
maximum operating temperature the portions of
The diameter across the thrust face axis in the
head portion of a piston constructed according
to‘ my invention is less than the diameter across
i
the same axis in the skirt portion, and referring
to the drawing in Figure 1 I have shown a piston >
arranged within a cylinder with the piston head 5 >
and the land portions 6, ‘I, 8 and 9 bearing
against‘ the cylinder wall at one side of the piston.
i
the ring lands at the ends of the major axis are . Since the diameter across the thrust face axis B
in close bearing relationship with the cylinder
wall. Any excess in the length of the major axis
of the oval lands is removed by slight deforma
tion of the metal of the lands which is permitted
by the limited circumferential length of the lands
which ‘reach cylinder engagement.
‘"
Alternatively the ring lands may be constructed
75 in any shape so as to provide limited areas for
in the skirt portion I0 is greater than across the
same diameter in the head portion, this position
of the piston requires that the thrust face H be ,
?exed somewhat, and I have indicated this ?ex
ing on an exaggerated scale by the dotted line
1
i la. In other words, in the absence of any‘?ex
ingor yielding in the skirt portion, the skirt H
would be’positioned as at Ma, and thus prevent "
3
2,130,923
the lands 6 to 9 from hearing on the cylinder
wall. The condition illustrated in Figure 1
therefore assumes that a force is acting laterally
of the piston in the direction of the arrow A.
With normal or conventional clearances in
the skirt andhead portions, ?exing of the skirt
or tilting of the piston to bring the ring lands into
engagement with the cylinder as shown in Figure
1 would produce a noise or slap.
According to
10 my invention, however, the diameter of the
head portion across the thrust face axis B with
respect to the skirt portion across the same axis
is such that the permitted amount of movement
of the piston head is less than the movement
15 necessary to produce an audible slap. ‘Since both
the head and skirt engage the cylinder wall no
tilting of‘ the piston can take place. The move
ments of the piston throughout its cycle of op
eration, therefore, are substantially straight ver
20 tical reciprocations.
As an illustration of the relative dimensions
that may be used in practicing my invention I
have found that in constructing what is known
as a “three inch piston", the skirt may be ma
25 chined to have a diameter across the thrust faces
. of 2.998 inches, and that the head portion or
piston land constructed according to my inven
tion may be machined to, havev a diameter of
' 2.994 inches. Those skilled in the art. will read
30 ily appreciate that with a conventional or round
cross section piston land, such clearances would
be impossible, and that such standard or con
ventional round head would score and seize. I
have found by test that a piston constructed ac
35 cording to my invention and having the clear
ances as above pointed out operated successfully
withoutout any drag or scoring or seizing.
Inpistons constructed in accordance with the
present invention, as in the conventional pistons
of the prior art, the temperature of the piston
head, and therefore‘ the necessary amount of
clearance, varies considerably with the conditions
of service of the piston such‘ as the average heat
of combustion developed in the combustion
gr’essively decreasing clearance, the amount of
decrease also depending upon the conditions of
operation of the piston in the engine. It will
be understood, of course, that the present inven
tion is not limited to ‘all of the ring lands being
provided with hearing faces as described.
Among the reasons for freedom from drag
or scoring in a piston having such small clear
ances in the head portion is the reduction in
contact area between the head and the cylinder 10
wall. By reference to Figure 2 it will be observed
that the bearing contact between the piston head
and the cylinder wall is restricted to narrow
vertical sections D and D' at the ends of the
thrust face axis indicated at B. The head por
tion is thus free of cylinder wall bearing con
tact throughout the major‘portion of its pe
riphery;~
.
When the piston heats up in operation both the
skirt and the head increase in size and tend 20
to reduce the clearance from the cylinder wall.
The increase in size of the piston skirt in the
type of piston having a yieldable skirt is ab
sorbed by yielding'or ?exing of the skirt. This '
reduces the difference between the length of the 25
major axis of the ring lands and the diameter
through the centers of the thrust faces of the
skirt until at full operating temperature these
two diameters become substantially equal. That
is to say, the skirt reaches full bearing engage 30
ment with the cylinder wall. Should the piston
head be heated to a- point that it will tend to
expand beyond this point the excess expansion
is absorbed either by yielding of the ring ?ange
as a whole so that the lower lands tend to be 35
pressed to a more nearly circular form, or by ac
tualt deformation of the metal of the lands.
Such deformation of the lands without binding
or scoring in the cylinder is permitted because of
the limited circumferential length of the portions 40
of the lands which engage the cylinder wall. The
lands at and near the top of the piston head can
not yield from their oval form whereas the lower
portion of the ring ?ange may yield slightly.
Accordingly, the lower ring lands may be pro 45
.vided with less clearance at the ends of their
major axis than the upper lands or the length
of the vmajor axes of the ring ?anges may in
crease or taper slightly from the uppermost to
the lowermost land.
50
In some instances it may be desirable to fur
. zontal slots separating or partially separating the ther reduce the area of engagement of the ring
head from the skirt, the 'amount of metal in the lands with the cylinder wall by reducing the ver
ring‘ ?ange and. in the connecters between the tical height of the portions which engage. Three
head and the skirt, the number and size of the alternative ways in which this may be done are
piston rings, etc. In the example given above illustrated in Figures 3 to 5, inclusive
In Figure 3 the lands 6a to 90. inclusive are
the radial clearance of the uppermost ring land
at the ends of the major axis perpendicular to each provided with a bevelled portion i3, which
the wrist pin axis would be .001 of an inch per reduces the axial or vertical extent of the por
60 inch of piston diameter. Where the vertical tion of the land which may bear against the cyl 00
width or extent of the ring lands is reduced by in ‘ wall. In Figure 4 the lands 6b to 9b may
chamber and the facility with which the piston
conducts away the heat imparted to it. The rate
at which the piston head transmits’ to the oil
and the cylinder walls the heat which is imparted
to it by the combustion ‘chamber depends in
turnL on a, number of factors of the piston de
sign including the number and extent of hori
‘ any of the arrangements shown in Figures 3, 4
or 5, or in similar ways, this clearance may be
reduced. I have used the expression “about .001
of an inch. per inch of piston diameter” to de
fine this clearance relation as given in this ex
ample and immaterial variations thereof which
do not depart from the operation vand results
characteristic of the present invention. In cor
responding types of pistons embodying the con
ventional ring ?ange of the prior art the essen
*
:oved as at id to obtain a like reduction in
the axiai extent oi‘ the bearing surface. In Fig
ure 5 the lands to; to 9d inclusive are illustrated
as being -f‘step-cut” to leave annular ridges l5. 65
It is to be understood that the land structures
illustrated in Figures 3 to 5 are to be employed
in combination with an out-of-round head por
tion, for instance, such as illustrated in Figure
2 or 6.
In such combination each of said land
modi?cations will function somewhat differently
tial minimum radial clearance varied from .002 l and each is suited to a particular type or style
to .0035 of an inch per inch of piston diameter.
The lower ring lands both in the present inven
75 tion and in the prior art may, be given a- pro
of combustion engine or piston skirt construc
tion. Since the modification of Figure 5 presents
the least vertical extent of cylinder bearing con 75
' 4
2,130,923‘
tact surface, it would be especially suited for use
skirt portion having opposed wrist pin bosses, ‘an
_ in a motor wherein the laterally acting forces,
such as indicated at 8 in Figure 1,’required but
slight resistive action in the lands of the head
portion. The modi?cation of Figure 5 also has
integrally formed head and ring ?ange provided
the advantage that the slight bearing contact
surface will permit a rapid “wearing-in” of the
land structure, and it also offers a factor of
safety in the event of excessively high tempera
10. tures in the head portion.
The modi?cation of Figure 4 is designed par
ticularly to improve lubricating characteristics
in the head portions, and the grooves it will,
during the normal operation of the piston, con
15 tain a quantity of oil integral with the cylin
drical ?lm of oil about the piston, and will serve
3. A piston for internal combustion engines 10
having a skirt portion provided with opposed
thrust faces, pin bosses arranged on an axis
vnormal to the axis across said thrust faces, an
integrally formed head and ring ?ange, said skirt
being yieldable to permit the same to ?ex in re 15
sponse to laterally. acting forces during piston
as a reservoir to maintain this ?lm adjacent the
operation, said head and ring ?ange propor
tioned to~present an oval cross sectional contour"
.
throughout the height of the ring ?ange with
signed to operate generally as in the embodi
ment of Figure l and the bevelled corners of the
the majoraxis of said oval coincident with said 20
thrust face axis, the diameter across the thrust
ring lands as at I3 will insure thatthe metal
on the vertical face of the lands will not effect
a peening action on the rings within the grooves.
face axis in the head and ring ?ange propor
tioned with respect to the diameter of the skirt
25 For instance, excessive expansion in the head
portion due to high operating temperatures may
cause a?ow or Working of the metal vertically
along'the land during piston reciprocation, and
it is important that this Working of the metal be
accommodated so as to prevent a binding of the
piston ring within its groove.
- In the event that a piston is proportioned or
‘designed so as to permit a tilting or movement
in the direction .of the wrist pin axis the head
portion may be contoured according to my in
vention as illustrated in exaggerated scale in
Figure 6. In this form of piston ring land con
struction the head portion is shaped to provide
a cross section wherein oval bearing portions; are
40 presented on the wrist pin axis C as well as on
the thrust face axis B. The piston head presents
t a constantly increasing deviation from the cir
cle de?ned by the cylinder to approach a maxi
mum at points indicated at E intermediate the
45 pin boss thrust face axes B and C. In this form
ofJny invention I appreciate that~it may be
necessary to reduce actual bearing contact 'area
or provide a greater clearance between the head
and the cylinder wall across the thrust face axis
50 at B than in the preferred embodiment illus
trated in Figure 2.
Although I have described certain embodi
ments of my invention in considerable detail, it
will be understood that thoseskilled in the art
55 may effect certain changes without departing
from the scope of the invention and'that, there
fore, I do not wish to be limited to the speci?c
devices shown, but rather by the appendedv claims.
Iclaim:
60
to guide the piston during reciprocation.
head of the piston.
The modi?cation illustrated in Figure 3 is de
'so
with an oval cross sectional contour throughout
its height, the major axis of said oval arranged _‘
normal to the‘ pin boss axis, the diameter of the
head and ring ?ange portion‘ across said major
axis being proportioned with respect to said skirt
portion to bear against the wall of said cylinder
_
1. A piston for internal combustion engines
comprising a skirt having wrist pin’ bosses there
in, and thrust faces on an axis normal to the
to bear against the wall of. the cylinder within
which the piston operates whereby to guide the 25
same in a truly straight line reciprocation.
4.. A piston for internal combustion engines
comprising a skirt portion having opposed wrist
pin bosses, a head and ring ?ange integral with
said skirt above said pin bosses andseparated 30
froi’n said skirt on each side of said pin bosses
by a horizontally extending slot, said head and
ring ?ange provided with a non-circular cross
section throughout the height of the ring ?ange
having its‘ maximum diameter normal to the axis 35
along said pin bosses and proportioned to bear
against the cylinder wall above said horizontal
slot whereby to guide the piston vertically during
its reciprocation.
-
5; A piston for an internal combustion engine 40
comprising a skirt portion having opposed wrist
pin bosses, opposed thrust faces arranged upon an
axis normal to the axis along said wrist pin bosses,
a head and depending ring ?ange integral with
said skirt above said wrist pin bosses and separat: 45
ed from said skirt by a horizontal slot above said
thrust faces, said head and ring ?ange shaped to
provide an oval cross section throughout the height
of the ring ?ange with the major axis arranged
normal to said pin boss axis, the diameter in the 50
head and ring ?ange on said major axis being
proportioned with respect to the axis across the
thrust faces in the skirt portion of the piston to
permit said head and ring ?ange portion to bear
against the wall ofthe cylinder in which the 55
piston operates immediately adjacent said major
axis to prevent tilting of the piston in the direc
tion ofsaid major axis in response to forces act
ing laterally upon the piston during operation.
6. In an internal combustion engine, a cylinder 60
having a circular cross-section, and a piston re
ciprocable in said cylinder including a skirt por
wrist pin axis, a head 'having a depending ring
?ange integrally formed with said skirt, said
tion having opposed wrist pin bosses, an integral
ly formed head having a depending ring ?ange,
65 ring ?ange having a non-circular cross sectional said head and ring ?ange provided with an oval 65
contour having bearing portions arranged imme
cross sectional contour, ring lands formed on said
diately adjacent the wall of the cylinder in which ~ depending ring ?ange and each provided with
the piston operates at the pin boss axis and at an oval contour corresponding to the head and
the thrust face axis, and portions intermediate ring ?ange, said ring lands being cut away on
each of said bearing portions having a greater their edges to provide a space intermediate the
clearance with respect to the walls of the cyl
outer periphery of the ring land and the rings
inder than said bearing portions.
between said lands.
'
2. In an internal combustion engine, a cylin
7. In an internal combustion engine, a cylin
der having a circular cross-section, and a piston
reciprocable in said cylinder provided with a
der having a circular cross-section, and a piston
reciprocable in said cylinder including a, skirt
2,130,928
portion provided .with opposed wrist pin bosses,
5,
in upon an axis normal to the axis of said wrist
an integrally formed head having a depending
pin bosses, ahead and a ‘depending ring ?ange
ring ?ange, said head and ring ?ange provided
secured to said skirt above said wrist pin bosses
and separated from said skirt by a horizontal
slot above'said thrust faces, the upper surface of
said head and said ring ?ange shaped to provide
' with an oval cross sectional contour throughout
the height of the ring ?ange, the major axis of
said oval arranged normal to the axis along said
pin bosses, ring lands formed on said depending
ring ?ange, said ring lands being cut away on
their edges to provide a space intermediate the
10 outer periphery of the ring land and the rings
between said lands.
an oval head section above one of said thrust
faces, the major axis of said oval head section
extending normal to said pin boss axis, the maxi
mum diameter of said head and ring ?ange being
across said major axis and the piston being pro
8. In an internal combustion engine, a cylin- ' portioned to provide a maximum diameter across
der having a circular cross-section, and a piston - said thrust faces exceeding a maximum diameter
'15
"reciprocable in said cylinder including a skirt
portion provided with opposed wrist pin bosses,
an integrally formed head having a depending
ring ?ange, said head and ring ?ange provided
of the head along said major axis thereof.
13. In an internal-combustion engine, a cylin- T.
der having a circular cross-section, and a piston
reciprocable in said cylinder comprising a head
and skirt portion, said skirt having opposed wrist
the height of the ring ?ange, the major axis of pin bosses therein, said head having a non-cir
said oval arranged normal to the axis along said cular.cross sectional contour providing spaced '
pin bosses, the diameter in the head and ?ange curved bearing surfaces and alternate spaced re
across said major axis proportioned with respect ‘ lieved areas having a greater clearance with re
spect to said cylinder than ‘said curved bearing
to ‘the corresponding diameter/in the skirt por
surfaces, said bearing surfaces and relieved areas
tion and with respect to the diameter of the cyl
inder to permit said head and ring ?ange to bear extending downwardly from the upper edge of
against the cylinder wall and guide the piston, the head, at least one of said curved bearing sur
ring‘ lands formed on said depending ring ?ange, faces arranged on an axis normal to the wrist
said ring lands being cut away on their edges to pin axis to prevent tilting of the piston within
provide a space intermediate the outer periphery the cylinder about said wrist pin axis.
14. In an internal combustion engine, a cylin
of the ring land and the rings between said lands.
der having a circular cross-section, and a piston
9. In an internal combustion engine, a cylin
der having a circular cross-section, and a piston reciprocable in said cylinder comprising a head
reciprocable in said cylinder comprising a skirt and skirt portion, said skirt having opposed wrist
having wrist pin bosses therein and thrust faces pin bosses therein, said head having a non-cir
with an’ oval cross sectional contour throughout
'20
on an axis normal to the wrist pin axis, and a
cular cross sectional contour providing spaced I
curved bearing surfaces, each of said curved
bearing surfaces presenting a constantly increas
ing deviation from said circular cylinder, and
said thrust faces, each of said bearing'faces pre- > alternate spaced relieved areas having a greater
.40 senting circumferentially a constantly increasing clearance withv respect to said cylinder than said Mi
deviation from said circular cylinder, the area curved bearing‘ surfaces, said bearing surfaces
of least clearance on said ‘bearing faces being and relieved areas extending downwardly from
the upper edge of the head, at least one of said
coincident with the axis of the thrust faces nor
curved bearing surfaces arranged on‘ an axis
mal to the wrist pin axis. _
.
normal to the wrist pin axis to prevent tilting of
10. In an internal combustion engine, a cylin
' der having a circular cross-section, and a piston the piston within the cylinder about said wrist
‘reciprocable in said cylinder comprising a skirt pin axis.
15. In an internal combustion engine, a cylin
having wrist pin bosses therein and thrust faces
on an axis normal to the wrist pin axis, and a der having a circular cross-section, and a piston
head having a depending ringw?ange provided reciprocable in said cylinder including a head
head having a depending ring ?ange provided
with curved ‘bearing faces extending downwardly
from the upper edge of the head above each of
with curved bearing faces extending downwardly
and skirt portion, said skirt portion provided with
from the upper edge of the head above each of
opposed wrist pin bosses and thrust faces ar
ranged on an axis normal to the axis of said wrist
said thrust faces, atleast one of said'bearing
faces ‘presenting circumferentially a constantly
55 increasing deviation from said circular cylinder,
the area of‘ least clearance on said one bearing
face being coincident with the axis of the ‘thrust
face normal to the wrist pin axis. ,
, 11. Inan internal'combustion engine, a cylin-_
der having a.v circular cross-section, and a piston
reciprocable in said cylinder comprising a head
65
pin bosses, said thrust faces separated from the
head of the piston by a horizontal slot above each
of said faces and arranged to ?ex independently
of said head in response-to lateral thrust, said
head having a non-circular cross section with a
maximum diameter coincident with the axis of
said thrust facesand being relieved on each side
of said axis, the diameter of ‘said piston across
said thrust faces exceedingv the diameter of the
head portion thereabove and ?exing in response
to lateral thrusts to bring said head into cylinder
and skirt portion, said head portion comprising
an integral casting solid throughout the perim
eter and said skirt portion being ?exible, said
skirt portion provided with thrust faces on an wall bearing contact and prevent tilting of the
axis'normal to the wrist pin boss axis, said head piston within the cylinder about the wrist pin
’ ‘ portion having
a non-circular
cross
sectional
16. In an internal combustion engine, a cylin
contour extending downwardly from its upper’
edge with ‘a maximum diameter coincident with der circular in cross-section and a piston recip
rocable therein comprising a head having a crown 70
.70 the axis of said thrust faces, said maximum di
ameter being less than the maximum diameter , and 9. depending ring ?ange, and a skirt having
aligned wrist pin bosses, said crown and ring
across said thrust face axis.
_
12. A piston for an internal combustion engine ?ange being oval in cross section throughout
comprising a skirt portion having opposed wrist their height, with the major axis of the oval
perpendicular to the wrist pin axis.
75 pin bosses, opposed thrust faces‘arranged there
2,130,923
6 .
17,. In an internal combustion engine, a cylin
18. In an internal combustion engine, a cylin
der circular in cross-section and a piston recip . der circular in cross section and a pistonrecip
rocable therein comprising a head, wrist pin rocable/therein, comprising a head, wrist pin
bosses, and a skirt, said skirt having thrust faces bosses, and a skirt, said skirt having thrust faces
on an axis normal to‘ the wrist pin axis and
bearing on said cylinder, said‘head having a de
pending flange grooved on the outside to receive
packing rings and to provide circumferential
lands on opposite sides of the grooves, at least
10 one of said lands being in a plane above said wrist
pin axis and having a non-circular sectional con
tour providing a bearing face above one of said
thrust faces, the clearance between the cylinder
on an axis normal to the wrist pin axis’ and
bearing on said cylinder, said head having 9.
depending ?ange grooved on the outside to re
ceive packing rings and to provide circumferen
tial lands on opposite sides of the groove, at leastv
‘one of said lands being in a plane above said 1,0
wrist pin axis and‘ having a non-circular sec
tional contour providing a bearing face above one
of said thrust faces, the clearance of said bearing
wall and the bearing face of said last mentioned
15 land being of such dimension as to permit the
said bearing face to bear against the cylinderv
face from the cylinder wall when the piston'is
cold and centered within the cylinder being‘ about
wall and serve as a guide to prevent-tilting of
said one land having portions of substantially
the piston and thereby restrict the piston to a
greater clearance from the'cylinder wall adjacent
such bearing face.
truly vertical reciprocation within the cylinder
20
and avoid audible slap.
'
'
'
.001 of an inch per inch of piston diameter, and
FRANK JARDINE.
20
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