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Патент USA US2127461

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Aug. 16, 1938.
FiledA March 11*?, 193s
ROLAND c/fJLro/v
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Patented Aug. 16, 1938
Roland Chilton, Ridgewood, and Rudolph F.
Gagg, Fair Lawn, N. J., assignors, by mesne as
signments, to Wright Aeronautical Corpora
tion, Paterson, N. J., a corporation of New York
Application March `17, 1936, Serial No. 69,290
4 Claims.
This invention relates to the attachment of
cylinder heads to cylinder barrels, and particu
larly comprises improvements in the screw thread
type of joint now in use in air-cooled aircraft
5 engines.
(Cl. 285-55)
, While we have described our invention in de
tail in its present preferred embodiment, it will
be obvious to those skilled in the art, after under
standing our invention, that various changes and
modifications` may be made therein without de- 5
parting from the spirit or scope thereof. We aim
in the appended claims to cover all such modiñ
'The conventional construction comprises an
.aluminum head screwed onto a steel barrel and
many failures in the aluminum are caused by
fatigue cracks engendered by the stress concen
10 tration which occurs at the sharp corners of
the threads.
To overcome this difficulty it has been sought
to use forged rather than cast aluminum alloys
for the heads, but this involves a great increase
in fabrication cost, in view of the excessive
material of low strength `and fatigue resistance,
amount of machining required in producing the
required linning from solid forgings.~
The prime object of the present invention is
said cylindrical member and engaging within
said groove, whereby tensile stress between respec
to eliminate from the stressed portion of the head
cations and changes.
What is claimed is:
1. In a joint, an integral outer head member of 10
said member having a cylindrical recess, an inner
cylinder member engaging within said recess and
extending therefrom, the recess having an annu
lar groove, and a high strength and fatigue re
sistant ring in screw threaded engagement with
tive members is carried through said ring. ‘
20 material the stress concentrations due to the
2. In apparatus of the class described, an in
threads, and thus to increase the strength and
fatigue resistance of the structure.
The drawing is a fragmentary axial section
through a cylinder head embodying the inven
tion. In this drawing the head comprises the
lower portion Il] equipped with the valve seats
tegral head member having a cylindrical sided
I2 and fins, shown as to their boundaries only,
by the dotted lines I4. A conventional cylinder
barrel I6 has screw threads I8 and i'lns 20 there
30 on. According to the provisions of this inven
tion, instead of forming the companion threads
in the material of the head I0, an annular recess
having a very large radius or fillet 22 is provided
and into this recess there is expanded, as by roll
35 ing, a ring 24 preferably of forged aluminum ma
terial. After the ring 24 is expanded into the
head l Il, the bore of the ring is threaded. There
upon, the cylinder head, with the ring 24, is
brought to an elevated temperature and is assem
40 bled to the steel barrel IE, the threads of the ring
24 engaging the threads I8 of the barrel I6, and
the smooth bore of the head itself engaging the
smooth surface of the cylinder below the threads.
It will now be seen that all sharp corners have
45 been removed from the material of the head III
and the large radius 22 substituted; this comprising the abutment between the head and the ring
recess and an annular groove therein, said groove
having an arcuate profile, a ring of material
stronger than the member filling said groove and
having threads formed in its recess, and a cyl 25
inder smoothly engaging within said recess hav
ing threads engaging the threads of said ring.
3. In a joint, a light alloy integral head mem
ber having a recess and an annular groove within
the recess, a ring of material stronger than the
member within said groove and in contact with
the groove surface, said ring having screw threads
formed on the bore thereof, and an externally
threaded member screwed into said ring and
smoothly engaging the surface of said recess. 35
4. In a. joint between an annular integral head
member and a tube member, the head member
being of relatively weak material of such a char
acter .as not to have adequate strength for screw
threaded engagement with the tube member, 40
said head member having a smooth cylindrical
recess and an annular groove of arcuate proñle
in the cylindrical part of the recess, a strong
ring capable of supporting screw threads, and
having same in its bore, disposed within said
> groove and in bearing engagement with the sur
face thereof, said tube member smoothly engaging
2li by which the explosion forces to which the head
said bore and having external threads in screw
is subject are resisted.
50 in this construction the ring 24 may be made
of -forged. material, and further, that the loads
engagement with threads of said ring, whereby
relative tensile stress between said head and tube
members is resisted by the strong ring compres
between threads I8 and the curved abutment
shoulder 22 are compressive and so do not tend
sively bearing on the surface of the head member
groove and by the screw threaded connection
It will also be seen that
to produce the tension fatigue cracks which have
55 been experienced when these threads have been
formed directly in the cast material of the head.
between the tube and ring.
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