Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1999-12-16
2001-11-06
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S430000
Reexamination Certificate
active
06312159
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bearing metal positioning structure in a split connecting rod, particularly to a bearing metal positioning structure with low production costs and improved accuracy of positioning the bearing metal.
2. Background Art
In general, a bearing metal composed of a pair of bearing metal halves, each of which is formed into a 180 circular-arc shape in cross-section, is inserted in a large-diameter end portion of a split connecting rod for an internal combustion engine. An oil film is formed between the bearing metal and a crank pin to lubricate between the connecting rod and the crank pin.
The pair of bearing metal halves are mounted between a rod side upper half and a cap side lower half of the large-diameter end portion while being positioned so as not to move in the peripheral direction and in the axial direction.
To effect the positioning of the bearing metal halves, in general, a projection is formed at one of both the peripheral ends of each bearing metal half formed into a 180 circular-arc in cross-section. As shown in
FIG. 11
of this application, locking grooves
05
b
and
05
a
are formed in the inner peripheral surfaces, on the mating plane sides, of upper and lower halves of the large-diameter end portion of the split connecting rod, respectively. The positioning of the bearing metal halves is performed by engaging the projections in the locking grooves
05
b
and
05
a
(see Japanese Patent Publication No. Hei 2-19328, and Japanese Patent Laid-open No. Sho 61262219).
FIG. 11
is a schematic partial view, seen from the inner peripheral surface
01
d
side, of large-diameter end portion
01
a
of a split connecting rod. In
FIG. 11
, reference numeral
02
designates an upper half of the large-diameter end portion, and
03
is a lower half (cap side half) of the large-diameter end portion. The inner peripheral surface
01
d
forms a bearing hole for rotatably supporting a crank pin.
In the above method, however, because the halves
02
and
03
of the large-diameter end portion
01
a
of the split connecting rod are separately machined to form the locking grooves
05
b
and
05
a
in the inner peripheral surfaces, on the mating plane sides, of the upper and lower halves
02
and
03
, production costs are raised.
When the split connecting rod is configured as the breaking-split connecting rod, an integrally die-formed body is broken along a breaking plane C. The die-formed body is formed into the rod side half containing the upper half
02
of the large-diameter end portion
1
a
, and a cap side half being the same as the lower half
03
of the large diameter end portion
1
a.
The rod side half and the cap side half are assembled into one body, and the locking grooves are mechanically finished in the assembled state. In this case, only the paired locking grooves opposed and communicated to each other with the breaking plane C can be mechanically finished. The locking grooves
05
b
and
05
a
located on the opposed sides with respect to the breaking plane C at different axial positions cannot be mechanically finished.
To mechanically finish the locking grooves
05
b
and
05
a
, the locking groove
05
b
of the rod side half and the locking groove
05
a
of the cap side half must be separately, mechanically finished before assembly of the rod side half and the cap side half into one body. This likely results in damage to the breaking plane C during machining.
Further, if the split connecting rod is configured as a breaking-split type connecting rod, the breaking plane C of an integrally die-formed body becomes bearing metal locking planes
017
b
and
017
a
in the circumferential direction of the locking grooves
05
b
and
05
a
, which degrades the accuracy of positioning the bearing metal.
An object of the present invention is to solve the above-described problems of the related art bearing metal positioning structure in a split connecting rod, and to provide a bearing metal positioning structure in a split connecting rod with reduced production costs by eliminating the necessity of machining locking grooves on the split connecting rod side, and improving the accuracy of positioning the bearing metal.
Another object of the present invention is to provide a bearing metal positioning structure in a split connecting rod which is less likely to involve error in assembling the bearing metal in the split connecting rod.
SUMMARY OF THE INVENTION
The present invention achieves the above objects and other advantages not contemplated by the conventional art. The present invention is addressed to a bearing metal positioning structure in a split connecting rod for mounting a bearing metal in a large-diameter end portion of the split type connecting rod. The bearing metal is composed of a pair of bearing metal halves, each of which is formed into a 180 degree circular-arc shape. The pair of bearing metal halves have flat planes (mating planes) which abut to form a cylindrical bearing metal.
A pair of projections are disposed on each of the mating planes at both axial ends which project radially outwardly therefrom, and locking grooves to be engaged with the pairs of projections are integrally die-formed simultaneously with the production of a die-formed body of the split connecting rod.
As a result of this configuration, by the engagements between pairs of the projections and the locking grooves, it is possible to restrict the movement of the bearing metal in the peripheral direction and the axial direction, and to accurately perform the positioning of the bearing metal halves. Further, it is possible to eliminate the necessity of machining works for forming the locking grooves, which lowers production costs.
In addition, the locking grooves are formed at both axial ends of a large-diameter end portion of the split connecting rod.
Since the locking grooves are each formed into a shape in which the axial end of the locking groove is opened, they can be easily die-formed upon the production of a die-formed body of the split connecting rod. Further, by engagement of pairs of the projections of the bearing metal halves in these locking grooves, it is possible to restrict the axial movement of the bearing metal halves and hence to restrict the axial movement of the bearing metal.
The split connecting rod is configured as a breaking-split type connecting rod, and the locking grooves are integrally-die-formed in such a manner as to be opened to a breaking plane or penetrated by the breaking plane.
As a result, starting points of breaking can be set at these locking grooves, to thereby facilitate the breaking work. When a pair of locking grooves are formed on the rod side upper half and the cap side lower half at both the axial ends of the large-diameter end portion of the breaking split-type connecting rod in such a manner as to be opposed and communicated to each other with respect to the breaking plane, a pair of locking grooves can be integrally die-formed as one large locking groove simultaneously with the production of a die-formed body of the breaking split type connecting rod. Consequently, the locking grooves can be easily die-formed.
Since the locking grooves are integrally die-formed simultaneously with the production of a die-formed body of the breaking-split type connecting rod, the locking portions of the bearing metal halves in the peripheral direction are determined at specific positions of the integrally die-formed body, and are not affected by the breaking manner for breaking the integrally die-formed body. It is therefore possible to improve the accuracy of positioning of the bearing metal. Also, with this configuration, since the limitations on the breaking position of the integrally die-formed body can be relaxed, breaking work is simplified.
A recessed groove having a notch portion functioning as a starting point of breaking is formed in the inner peripheral surface of the large-diameter end portion of the breaking split-type connecting rod and extends along the breaking plane.
Ishida Masao
Kato Tadashi
Kinoshita Toyotaka
Tosaka Tetsuya
Birch & Stewart Kolasch & Birch, LLP
Hannon Thomas R.
Honda Giken Kogyo Kabushiki Kaisha
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