Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a connecting rod bearing for the crankshaft
journals and piston pins of combustion engines, said bearing comprising a bush
in the end of the connecting rod, and to a method for producing the said bearing.
Connecting rod bearings in the form of bearing shells are known
~German Patent 971,746) which are divided radially or axially to facilitate
assembly, and which have side flanges. Bearing designs of this kind are
particularly unsuitable for roller bearing connecting rods, since, in rolling
over the joints in the bearing surface, the rollers produce shocks which cause
vibration. In the case of axially divided bearing shells having side flanges,
on the other hand, it is impossible to provide positive means to prevent axial
displacement, and additional arrangements are needed to that end.
Also known for connecting rod bearings, for example piston pin bearings,
are cylindrical bushes (German Patent 960,514), but these must also be additional-
ly secured against axial displacement. Moreover, this design lacks thrust and
guide surfaces at the two end faces.
Also known for connecting rods are roller bearings in which the ends
of a thin walled ring are shaped inwardly. Although this provides axial thrust
surfaces, it may impede very considerably the supply of lubricant to the roller
bearing. Furthermore, this design cannot be relied upon to prevent axial
displacement.
Also known are hardened connecting rods, made of steel for example,
for the purpose of obtaining hardened bearing surfaces for needle bearings. The
process of hardening connecting rods of this kind requires additional labour and
thus increases production costs. Furthermore, a steel connecting rod is
relatively heavy as compared with a light alloy rod, although the latter requires
additional components for the thrust and guide surfaces.
It is the purpose of the present invention to provide a connecting rod
bearing which requires little labour to produce and may easily be secured to the
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big or little end of the rod against rotation and displacement. It is also a
purpose of the invention to provide a connecting rod which is relatively easy
and inexpensive to produce.
To this end, according to the invention, there is provided a connecting
rod bearing for crankshaft journals or piston pins of combustion engines,
comprising a bush composed of steel and held in a connecting rod end, the ends
of said bush being formed into flanges, characterized in that the bush is composed
of hardenable steel, that a cylindrical centre part of the bush is hardened to
provide a hardened cylindrical inner bearing surface for rollers and that at
least one of the flanges is not hardened. A bush of this design, arranged in
the connecting rod end, is secured in a structurally simple manner against axial
displacement by the fact that it is in one piece and by the two flanges bearing
against the side faces of the connecting rod end.
The flanges also form axial thrust and guide surfaces for a piston
or, if the bush is arranged in the connecting rod big end, for a corresponding
component.
Also according to the invention there is provided a method for
producing the bearing comprising hardening the cylindrical center part of the
bush, pressing the bush into the connecting rod end and thereafter forming said
at least one of said flanges that is not hardened into a flange bearing against
a side face of the connecting rod end.
One of the flanges may be formed before the bush is pressed into the
connecting rod end, or both may be formed after it is pressed in.
The connecting rod bearing according to the invention provides reliable
and inexpensive bearings in connecting rods made of unhardened materials, for
example light alloys. Light alloy connecting rods, in particular, reduce weight,
vibration and cost, and this is greatly facilitated by the bush according to the
invention.
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An embodiment of the invention is described hereinafter in greater
detail in conjunction with the drawing attached hereto, showing the end of a
connecting rod, in cross section, with a bearing for a piston pin or crankshaft
journal.
Connecting rod 1 comprises a shank 2 having two ends, one of which,
end 3, is shown.
Connecting rod end 3 comprises a bearing for a piston pin and/or
crankshaft journal running, for example, in a needlecage 4. The bearing in
end 3 is in the form of a one piece cylindrical bush 5 having side flanges 6
and 7. Bush 5 forms an outer ring having a bearing surface 8 for needles 14
in cage 4. The design of the connecting rod bearing is not restricted to piston
pins running in needlecages; other types of bearing are also possible. A
similar bush may also be used in the other end of the connecting rod.
The one piece outer ring is made out of a drawn, cylindrical, hardenable
sheet metal bush 5. Flanges 6,7 at each end of the bush extend radially outwards,
thus accommodating end 3 positively between them.
This design of bush 5, and the attachment thereof to end 3, makes it
possible to secure the said bush against axial displacement. In order to prevent
it from rotating in end 3J the said bush is provided with a chamfer 10. A
deformed area 11 at the edge of flange 6 or 7 projects into this chamfer.
For the purpose of producing the connecting rod bearing described
above, cylindrical bush 5 is provided with a flange 6 which is formed either
during production of the bush or in a subsequent separate operation.
Bush 5 is then heat treated for the purpvse of hardening central
cylindrical area 13 which forms the bearing surface 8 upon which bearing needles
14 will eventually run. At least one end of bush 5, end 12 which is still not
flanged, is excluded from this hardening process and thus remains soft. Such
partial hardening may be achieved, for example, by inductive or case hardening
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with a cover.
In a subsequent operation, this partially hardened bush 5 is pressed
into the bore of end 3 until flange 6 bears against a side face 9 or 9a of end
3. Freely projecting end 12 is then processed to form a flange 7. It is, of
course, also possible to form flange 7 first and then to form flange 6. This
operation ensures that bush 5 cannot be displaced in the bore of end 3. By
reason of their arrangement in relation to side faces 9, 9a of end 3, flanges 6,
7 form axial thrust and guide surfaces.
According to another configuration of the invention, bush 5 may be
secured against rotation in end 3 by pressing a portion of the edge of the
flange into a chamfer 10 in side face 9.
According to one advantageous embodiment of the invention, the connect-
ing rod is made of a light alloy and the bush of hardenable steel sheet. It
would, however, also be conceivable to make the connecting rod out of some
other, non-hardenable, material.
