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Патент USA US2136162

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Nov. s, 1938.
M. WARE
INTERNAL COMBUSTION ENGINE
Filed Jan. 30, 1935
2,136,162.
2,136,162
Patented Nov. 8, 1938
UNITED STATES PATENT OFFICE
2,136,162
INTERNAL COMBUSTION ENGINE
Marsden Ware, Detroit, Mich., assignor to Pack
ard Motor Car Company, Detroit, Mich, a cor
poration of Michigan
Application January 30, I935, Serial No. 4,060
6 Claims. (Cl. 309-1l)
This invention relates to pistons for internal 4 inclusive engaging in the cylindrical bore in an
engine cylinder 3. 4 indicates a connecting rod
combustion engines and more particularly to pis
and 5 a piston pin for connecting the piston with
tons for use in such engines.
one end of the connecting rod. The piston is
One object of the present invention is to pro
5 duce a novel and improved piston for internal provided with a head 6 formed with peripheral 6
combustion engines which is light in weight, grooves ‘I in which are ?tted piston rings 8 and a
strong and durable in construction and having a skirt 9 integrally attached directly to the head,
skirt which is capable of expansion under the preferably about the greater part of the periph
ery of the piston. The piston is provided with
high temperatures to which the piston is subject
piston pin bosses Ill in which the piston pin 5
10 ed in operation without undue friction against
the walls of the cylinder and which will prevent engages. These bosses are integrally connected
the passage between the same and the cylinder
wall of a greater quantity of oil than that re
quired for proper lubrication at any point in the
periphery of the piston.
Another object 01' the invention is to produce
an improved piston construction having a skirt
which is integrally attached to the head to form
a structure sufficiently rigid to withstand in a re
with the portion of the skirt extending between
the same and the head and ribs, one of which is
indicated at H, extend from the bosses along the
inside of the skirt to the head to give added
strength. The bosses are each directly and in
tegrally connected at the sides with the upper
part of the skirt and at the bottom with the por
tion of the skirt below the same. The peripheral
20 liable manner the strain of piston operation,
portion of the piston adjacent the piston pin
which is shaped to ?t closely to the cylinder wall
entirely about the periphery of the piston at one
bosses is relieved as indicated at I! to provide
ample clearance at all times between these por
or more points axially thereof and which will
tions of the piston and the cylinder wall
yield when expanded under the high tempera
tures within the engine cylinder.
With the above and other objects in view the
side of the piston by a transverse slot I3 and the
skirt is formed with a longitudinal slot I4 ex
invention consists in a piston construction em
bodying the novel and improved features herein
The head is separated from the skirt on one
tending downwardly from the slot l3 and termi
nating at some distance from the lower end of
the skirt. The transverse slot I3 reduces the
‘
after described and particularly pointed out in
heat conduction between the head and the skirt
30 the claims, the advantages of which will be read
' and the longitudinal slot l4 together with the
ily understood by those skilled in the art.
The invention will be clearly understood from slot i3 allow the upper portion of the skirt to
the accompanying drawing illustrating construc
tions embodying the invention in its preferred
35 form and the following detailed description of
the constructions therein shown.
In the drawing, Fig. l is a view partially in
side elevation and partly in vertical section il
yield during the expansion of the skirt.
In order to enable the portion of the skirt be
tween the piston pin bosses and the lower end
thereof to yield when expanded against the cyl
inder wall under the high temperatures to which
the piston is subjected in the engine cylinder,
lustrating an engine cylinder and a piston em
the skirt, in a zone between said bosses and the
40 bodying the invention engaging therein.
Fig. 2 is a view in horizontal section taken sub
lower end portion thereof, is given a cross section
normal to the piston axis in which the periphery
stantially on the line 2-—2 of Fig 2 with portions
of the piston and cylinder broken away.
Fig. 3 is a view in horizontal section taken sub
45 stantially on the line 3-3 of Fig. 1.
Fig. 4 is a view in horizontal section taken sub
stantially on the line 4-4 of Fig. 1.
Fig. 5 is a view in side elevation illustrating a
piston embodying the invention having a diil’erent
50 slot arrangement than that shown in Fig. l and,
Fig. 6 is a view in side elevation illustrating a
piston having a still different slot arrangement.
In the form of the invention shown in the
drawing, the invention is embodied in a piston
55 indicated as a whole at 2 and shown in Figs. 1 to
has the form of a convex curve and the diame
ter of the skirt in one direction is substantially
greater than another diameter perpendicular
thereto. In forming the piston skirt with a zone
of this cross section, the bearing surface is pref
erably made generally elliptical or oval the term
elliptical not being restricted to a bearing sur
face having the form of a mathematical ellipse.
In the construction shown, the skirt is made 50
elliptical in cross section normal to the axis in a
zone extending on each side of the line 3-3 of
Fig. l on which the section shown in Fig. 3 is
taken. In forming this elliptical cross section
the minor diameter or axis of the piston in said
2
2,186,182
zone is preferably located substantially parallel
with the axis of the piston pin bosses. The skirt
along said elliptical zone is arranged to engage
the wall of the cylinder at the respective ends of
the major diameter or axis and for some distance
on each side of the ends of said axis and to leave
a clearance at and adjacent the respective ends
of the minor axis as shown in Fig. 3. This clear
ance varies with the expansion of the piston in
10
the cylinder.
The difference in the length of the major and
minor axes of the piston in this zone may differ
in pistons of different size and also may be varied
in pistons of the same size. For example, it is
proposed to form the cross section in this zone of
a piston having a diameter of 31%" at the bottom
of the skirt so the major axis is at least .005 to
.007 of an inch greater than the minor axis. The
difference in the length of the major and minor
axes may, however, be made as much as .012 of
an inch or even more if desired.
To give the lower portion of the skirt a bearing
against the cylinder wall about the entire periph~
ery thereof and to prevent the passage of oil
between the skirt and said wall in excess of that
required for proper lubrication, the end portion
of the skirt remote from the head is made sub
stantially circular in cross section normal to the
axis and is arranged to ?t closely to said wall
30 at all points in the periphery of the skirt. The
skirt is preferably made substantially circular in
cross section in a relatively narrow zone at the
lower end thereof. This zone, however, may be
given any width to furnish the desired bearing
35 area for engagement with the wall of the cylinder
and to produce the desired results in the forming
of an oil ?lm between the skirt and said wall.
Fig. 4 is a section of the piston and cylinder taken
through this zone. This portion of the skirt will
40 act to spread the oil in a thin lubricating ?lm over
the inner surface of the cylinder and the lower
edge of the skirt will collect the excess of oil and
cause the same to be drained of! at the bottom
of the cylinder.
The zone of the piston skirt having an oval or
45
elliptical cross section preferably blends into the
zone having a circular cross section as shown in
Figs. 1, 5 and 6. Thus the minor axis of the skirt
in this zone gradually increases from the upper
50 to the lower portion of said zone and becomes
substantially equal to the major axis at the lower
end of said zone as shown in Fig. 1.
To enable the lower end portion of the skirt to
expand without binding against the walls of the
55 cylinder, the skirt is formed with one or more
slots i 5 extending upwardly from the lower end of
the skirt preferably to a point or points substan
tially opposite the lower end of the slot l4 periph
erally of the piston. Figs. 1, 2 and 3 show these
60 slots located in different positions about the
periphery of the‘ piston skirt. In the construc
tion shown in Fig. 1 the piston is provided with a
single slot l5 located on the same side of the skirt
as the slot l4 and generally in line with the slot
65 I4, axially of the piston.
In the construction
shown in Fig. 5 the piston is provided with two
slots l5, each located. substantially 90 degrees
from the slot ll about the periphery of the piston.
In the construction shown in Fig. 6, the piston
is provided with a single slot I! located on the
side thereof opposite the slot II and substan
tially 180 degrees from the slot ll about the
periphery of the piston.
In addition to the advantages above pointed
76 out, the above construction results in a piston
which is strong, sturdy and durable and in which
the skirt, because of its rigid connection with the
head except at the point at which the slot I3 is
formed, is not liable to get out of alignment
axially with the head. The strength of the con
struction enables the piston to be made lighter
than certain constructions now in extensive use
upon automobile engines. The skirt is suffi
ciently yielding to prevent the same from binding
against the cylinder wall when expanded and at 10
the same time has the stiffness required to enable
the same to withstand in a reliable manner the
strains to which it is subjected in operation. The
slots l5 allow the lower end portion of the skirt,
when expanded against the cylinder wall 2, to
yield sufficiently to prevent the same from bind
ing or exerting undue friction. The slots, how
ever, extend only a short distance upwardly from
the end of the piston and the lower end portion
of the piston is therefore fairly stiff.
As the increase in the length of the minor axis
of the skirt in the zone having an oval or elliptical
cross section tends to diminish the yieldability of
the skirt from the upper to ward the lower portion
of said zone, the slots l5 tend to give a ?exibility 25
to this part of the skirt progressively increasing in
the said direction.
It is to be understood that the invention is not
limited to the particular construction of the illus
trated embodiment of the invention but that the 30
said construction is merely illustrative of the in
vention and that the invention may be embodied
in other forms within the scope of the claims.
Having explained the nature and object of the
invention and having speci?cally described a con
struction embodying the invention in its pre
35
ferred form what is claimed is:
l. A piston for internal combustion engines
having a head, a skirt integrally connected at its
upper end directly with the head, and pin bosses
integrally attached directly to the skirt, the skirt
having a circular peripheral bearing surface at
the end remote from the head, said skirt having
its periphery relieved about the pin bosses and
the peripheral bearing surface intermediate the
circular bearing surface and the relieved portions
being elliptical in cross section normal to the axis
of the piston, the elliptical bearing surface blend
ing into the circular bearing surface axially of the
piston, said skirt having axially extending slots
therein terminating short of each other in the 50
elliptical cross sectional portion thereof.
2. A piston for internal combustion engines
comprising a head, a skirt integrally connected
at one end with the head and partially separated
therefrom by a slot extending transversely of the 55
piston axis, and a pair of aligned pin bosses on
the skirt, a slot extending axially of the skirt be
tween and co-extensive with the pin bosses and
connected with the transverse slot, and another
slot extending axially in the skirt from the end 60
opposite the head to a point short of the other
axially extending slot, said skirt being circular
in cross section at the end remote from the head
and ovate in cross sectional portion adjacent to
and between the axially extending slots.
3. A piston for internal combustion engines
comprising a head, a skirt integrally connected
at one end with the head and partially separated
therefrom by a slot extending transversely of the
piston axis, and a pair of aligned pin bosses on
the skirt, a slot extending axially of the skirt be
tween and co-extensive with the pin bosses and
connected with the transverse slot, and another
slot extending axially in the skirt from the end
75
2,186,162
opposite the head to a point short of the other
axially extending slot, said axially extending
slots being spaced circumferentially in the skirt
more than 90°, said skirt being circular in cross
section at the end remote from the head and
ovate in cross sectional portion adjacent to and
between the axially extending slots.
4. A piston for internal combustion engines
comprising a head, a skirt integrally connected
10 at its upper end directly with the head and par
tially separated therefrom by a slot extending
transversely of the piston axis, and a pair of
aligned pin bosses extending interiorly of said
skirt and formed therewith, said skirt having a
slot extending axially thereof between the pin
bosses and co-extensive therewith and connected
with the transverse slot, said skirt having another
axially extending slot spaced circumferentially
from the ?rst mentioned axially extending slot
20 and extending from the end of the skirt remote
from the head to a point short of the first men
tioned axially extending slot, the periphery of
said skirt surrounding said piston bosses being
relieved, the peripheral surface at the end of said
skirt remote from the head being circular and the
peripheral surface of said skirt adjacent to and
between the axially extending slots being formed
oval in cross section.
5. A piston for internal combustion engines
30 comprising a head, a skirt integrally connected
at one end directly to the head and partially sep
arated therefrom by a circumferentially extend
ing slot, and a pair of aligned piston bosses ex
tending interiorly of said skirt and formed there
3
with, the peripheral surface of said skirt being
relieved in the zones of the piston pin bosses, said
skirt having a slot therethrough extending axially
between the pin bosses and from the circumfer
cntial slot to a point substantially on a circum
ferential line with the relieved peripheral zones
of the skirt remote from the head, said skirt hav
ing another slot therethrough extending axially
from one of the relieved peripheral zones to the
skirt end remote from, the head, said skirt being 10
circular in cross section at the end remote from
the head and ovate in cross sectional portion ad
jacent to and between the axially extending slots.
6. A piston for internal combustion engines
comprising a head, a skirt integrally connected 15
at one end directly with the head and partially
separated therefrom by a circumferentially ex
tending slot, and a pair of aligned piston bosses
extending interiorly of said skirt and formed
therewith, said skirt having a slot extending axi 20
ally thereof between the piston bosses and co-ex
tensive therewith and connected with the cir
cumferentially extending slot, the periphery of
said skirt in the zones of the piston bosses being
relieved, the peripheral surface at the end of said 25
skirt remote from the head being circular and
the peripheral surface of said skirt from the cir
cular peripheral surface to the adjacent relieved
portions being ovate in cross section, and said
piston skirt having slots therethrough extending 30
axially from the relieved peripheral zones to the
end of the skirt remote from the head.
MARSDEN WARE.
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