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Патент USA US2007495

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Jußy , l935.,
Fileà „March 7, 19.55
Patented vJuly 9, 1935
j* l Y
, Alpheus Flower,
London, England
Application March 7, 1933, Serial No. 659,970r
In Great Britain March 9, 1932
(Cl. 309-14)
11 Claims.
This invention relates to multi-piece pistons eter. By this means the clearance between the
for fluid-pressure engines; and particularly to the exterior wall of the head or other part of the
bi-metallic kind comprising a crown or head cast metal and the inner wall of the steel skirt
formed of aluminium vor other light alloy, prefer can be reduced, thereby preventing any independ
5 ably as a casting, with integral wrist-pin or ent rocking of one part relatively to the other.
gudgeon-pin bosses or other body parts to. which
Figure l is a verti-cal section through the wrist
is attached a tubular skirt of cast iron, steel, or
pin or gudgeon-pin axis of one form of lai-metallic
some other good wear-resisting material.
The main object of the present invention is piston according to the invention;
VFigure 2 is a cross-section on the line II-II 1D
the provision of an improved method of and
means for attaching the skirt vto the head or some of Figure 1;
Figure 3 is a corresponding cross-section show
other piece of the piston Vwhereby said means
constitute `a device for compensating for the ing a modification;
Figure 4 is a vertical section through part
varying expansion and contraction of »the dif
ferentrmetals. A further object is to provide an of another. formof bi-metallic piston according 15
improvedarrangement with which the cost of `to theinvention; ‘
Figure 5 is a fragmentary vertical section indi
production will be reduced, particularly inasmuch
as it allows of `the head being cast independently cating another embodiment of the invention;
Figure 6 is a fragmentary vertical section, to
of the tubular skirt and subsequently securely
united to it in an inexpensive and simple manner. a somewhat larger scale, indicating a stepV in the ‘20
Furthermore, in the usual type of “cast-in” manufacture of the pistons shown in any of the
bi-metallic-pistons `the. contraction of the alu
bosses for the wrist-pins, etc., inside the skirt;
the figures.
, Figure 7 is `a similar View to that of'Figure 6,
minium from its hot state, after the casting op
eration, provides a clearance between thetwo but it shows a modiñed arrangement.
v25 »metals; that is, between the steel skirt andthe - Like numerals indicate like parts throughout V25
In »the constructions illustrated in Figures 1 to
and where thel skirt lmeets the head or lower
portionV of the ring belt of the» piston, or at the 4, showing a bi-metallic piston having a head 2
lower end of the skirt, the initial contraction of aluminium alloy, formed integrally with body
clearance is too great and- allows the head or webs 3; 3 from which the wrist-pin or gudgeon- y
other' parts to move relatively to the steel skirt. pin bosses 4, 4 are supported, and a tubular skirt
A further object of this‘invention is to obviate 5 of steel, the latter is provided peripherally, be
low where the wrist-pin will be, with a depression
this disadvantage.
~ »- Y
A piston, according to the main feature of the forming a substantially flat annular portion `(ì
invention, has a tubular skirt'provided periph the centre of which is in the longitudinal plane of k35
erally with a substantially flat disc or annular the skirt- through the wrist-pin axis.
In the arrangement of Figures 1 and 2, where
lportion through which the skirt »is attached to
another piece of the piston.
there is a single flat annular portion 6 on each
According to a further ‘feature of the inven
tion, the inner periphery of- the annular .portion
is surrounded by a iiange which extends inward
ly of the skirt and, engages the other‘piece of
the pistongfor attachment purposes. This flange
side, each of these has'ata its centre an aperture
surrounded by a frustum-shaped lflange l, the
\ end o-f which, in the interior of the skirt, is out
wardly-flared, as at 8, toprovide an increased
keying eifect with the circular metal boss 9, be
neath the wrist-pin bossesd, which is cast on to
may be frustum-shaped, with or without an out
wardly-iiared edge, or with or without a keying
According to a still further feature, the steel
skirt~has a portion, preferably at the top or
bottom thereof, ‘originally enlarged in diameter
externally, and after the metal of the head or
the flange 1.
Obviously the metal bosses 9 may be in the
form of a belt lll extending wholly, or partly, as
‘ shown in Figure 3, around the piston, and there
maybe two or more keying flanges 1 -on each side
' of the piston, as is also indicated byV Figure 3.
‘other Ípart of the piston has been cast and has The cast 'metal inside the flanges maybe ham
cooledfoff the skirt is drawn through a ring. of mered into contact therewith after cooling'.
'This latter figure also» shows a further method
the desired ñnal dimension of the skirt, or treat
ed in an equivalent manner, thereby bringing of securing the skirt through the annular por
'vt-"55 the" enlarged portion back to Athe'proper dia-m
tion 6 which may be Yused as' an alternative. to or `55
in conjunction with the arrangement of Figures on the cast metal in the vicinity of the skirt
1 and 2. In Figure 3 the non-circular head of enlargements during the casting operation.
a bolt II is embedded in the belt IIJ co-axial with When, however, the metal has cooled, the skirt
the flange 1, and the latter contains a nut I2 is drawn through a die, or treated in other
of similar outline and adapted, as by the pro
ways, such that the enlarged portions 26, 26
vision of serrations I3, to be screwed tightly on at its upper and lower ends are brought into
to the bolt after the cast metal has cooled and line with the remainder of its surface, as in
shrunk. Tightening the nut forces the flange dicated in Figure 1, where the upper end of
into contact with the surrounding metal.
The the skirt is shown in very close proximity to
nut can be locked by punching part of the bolt
into the serrations I3.
In the arrangement of Figure 4 the head, as
illustrated, is pre-cast and then bolted to the
skirt at the flat annular portions 6 of the latter.
Thus, the metal of the body of the head is also
the ridge 21.
Consequently, in spite of the fact that the
cast metal of the head may shrink from the
skirt, leaving an initial clearance, when finally
treated the clearance between the upper or lower
end of the skirt and the cast metal can be re
formed with a more or less similar depression I4 -duced to any requisite amount, and by this
that will engage the inner face of the fiat an means movement between the ends of the skirt
nular portion 6 but be elsewhere spaced from the and the cast metal can be entirely prevented.
The most inexpensive method of producing
20 bolt I5 with a fiat narrow head resting in the
skirt, to allow of expansion of the head body.
the skirt probably consists in the use of a skirt
depressionand not extending as far outwardly of uniform bore >and thickness, of which the
as the main portion of the skirt is passed through
the skirt land through a corresponding hole in
the Abody `portion of the head. At its inner end
there is a nut I6 which can be .tightened to lock
the skirt and body portion securely together.
ends can then be enlarged to the necessary di
ameter, as described above, in connection with
Figure 6. But an alternative method would con
sist in the use of a skirt of uniform bore and V.25
greater thickness at the two ends 26, 26 as shown
It is desirable to prevent relative rotation of in Figure '7, these thickened portions constituting
the nut on the bolt, and for this purpose a disc the skirt enlargements referred to above and be
washer I‘I may be interposed between the nut inging ilattened, as by being drawn through a
30 and the adjacent inner face of the body portion,
the washer being formed with outwardly-extend
`ing tangs I6, I8 of which one enters a hole I9
provided in the under-surface "of îthe wrist-pin
boss '4 to prevent rotation of the washer, Whilst
another tang can be bent up as shown to lock
the nut after it has been tightened. In like manner suitable holes 2U, 20 may be provided in the
bolt `andin the body 'portion to receive a short
stem or key 2| by which the bolt, when the nut
40 is tightened, vwill be locked against rotation.
>In a `preferredarrangement the bolt is formed
with an enlarged shoulder 22 beneath its head
(which is conveniently the portion of the bolt
drilled to receive the bolt locking member 2|)
45 -and this enlarged shoulder ñts the hole in the
die, after the cast metal has cooled.
In all cases, after the enlargements have been
ñattened, the clearances there should be such
as to allow of Contact being made internally of
the enlargements when the parts have expanded
under the normal working temperatures.
It will be seen that by means of the invention
a very ñrm and lasting attachment is evolved
which compensates for the varying expansions of
the two metals. The arrangement of Figure 4
lends itself to quick production; and furthermore 40
this piston may be economically manufactured.
In all cases the disc or annular portion 6 of
the depression in the skirt is ’sufliciently fiexibly
connected to the rest oi' the skirt to move as
the adjacent body portion of the head, which
is secured to it, expands.
provided in the body portion, acting totake the
What I claim as my »invention and desire to
’shear load.
secure by Letters Patent of the United States
As stated, in practice at least twosuch attach 1s:
50 Inent‘means’would be provided for a piston, these
1. A multi-piece piston having a head, a boss
being arranged diametrically opposite one an thereon, a tubular skirt, Vthis latter being pro
other. To facilitate assembly, a longitudinal vided peripherally on one of its non-thrust faces
-groove 23 is provided to receive the flat annular with a substantially flat circular portion through
portion 6 and its internal flange 24, which springs which the skirt is attached to the boss, -and a
into the hole in the head body.
nut and bolt, each of which is locked vagainst
In the modification of Figure 5, where the turning, for eiîecting said attachment.y
head is cast on tothe skirt, the flat annular por
2. A piston, according to claim 1, where the
tion 6 and the ilange 'I are co-axial with the head of the bolt lies against the outer face of
wrist-pin bosses 4. This construction is some the circular portion.
60 what lighter and cheaper to produce than that
3. A multi-piece piston having a head, a b_oss
of Figures 1 and 2. The keying effect is in thereon, a tubular skirt,»said skirt beingprovided
creased by the provision of the holes 25.
peripherally on one of its non-thrust faces with
4With a View to preventing relative movement a substantially ñat circular portion through
between >the head of the piston and the upper which the skirt is attached to the boss, anda
end of the skirt, these are preferably adapted in nut and bolt,l each of««which is locked against
the mannerillustrated in Figureß or Figure 7, turning, for eiTecting said attachment, said-bolt
where the clearances between the skirt and the having a hole therein, said piston adjacent the
cast metal are 'shown much exaggerated for the bolt having a mating holefand a pin -engaging
sake of clearness. There the skirt, prior to the in the holes for preventing 4the bolt from turn
70 casting operation, is not rof uniform bore; but at mg.
-its `upper and lower ends 26, 26 it isl enlarged
4. A bi-metallic piston comprising a head of
skirt and extends into a corresponding recess
slightly, as indicated in Figure 6 or '7.
light alloy, wrist-pin bosses integral with the
In >the arrangement of Figure 6, where the head, a tubular steel skirt provided peripherally
Vvskirt‘ehds are enlarged both internally and ex with depressions forming substantially flat an
Vter~nally,‘it follows that ridges 21,21 are formed nular portions, vsaid bosses having annular re- '
cesses about the outer ends thereof confronting
the inside of the skirt, said flat annular portions
seating in said recesses, and inwardly-extending
ñanges on` the iiat annular portions which are
co-axial with the Wrist-pin bosses.
5. A bi-metallic piston comprising a head,
bosses integral With the head, a tubular skirt,
a substantially ilat annular po-rtion on said tubu
lar skirt, said bosses each terminating. at their
nular portions, said body having annular recesses
to receive said annular portions, the centers of
said annular recesses lying in a longitudinal
plane with the axis of said openings, and means
uniting said annular portions to said body, the
external surfaces of said annular portions being
wholly out of contact with said body.
8. A piston, as claimed in claim '7, character
ized by each of said means being a tubular flange
outer ends in peripheral recesses and said annu of said annular portion.
9. A piston, as claimed in claim 7, character
lar skirt portion being received in a recess, and
means integral with the ñat annular skirt por ized by each of said means being a frustum
tion and extending inwardly of the bosses for shaped tubular ilange of said annular portion.
10. A piston, as claimed in claim 7, character
securing the skirt to the bosses.
6, A bi-metallic piston comprising a head, a ized by each of said means being a tubular ilange 15
body part integral With the head, Va tubular skirt of said annular portion, each of said tubular
surrounding said body part, a substantially flat lian-ges having an outwardly-flared edge Within
annular portion on the skirt, said body part hav said body.
11. A bimetallic piston comprising a head, a
ing a peripheral recess and said annular portion
being received in the recess, and means con body part integral With the head, a tubular skirt 20
necting said annular portion to said body part, surrounding the body part, the skirt having a
said means extending inwardly of said body part substantially flat annular portion merging, at
in the Vicinity of the recess thereinand the eX the ends of a diameter, directly into the tubular
ternal surface of said annular portion being portion of the skirt and said annular portion also
being connected with the tubular portion ofthe 25
wholly out of contact with said body part.
7. A loi-metallic piston comprising a head and skirt, at the ends of a diameter perpendicular to
body of light metal or alloy, said body having the first-mentioned diameter, by oppositely-slop
co-axial openings for a wrist-pin formed in it, ing portions, and means connecting said annular
a tubular skirt of steel or cast iron surrounding portion to the body part.
30 said body, said skirt being provided peripherally
with depressions forming substantially ñat an
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