Connecting rod

A multi-piece connecting rod has the large eye end formed with a yoke receiving a bearing bracket supported on an angled wedge surface by an angled counter surface of a wedge. The wedge is carried by a pin-like bolt between legs of the yoke and includes a threaded portion engaged by the bolt for tightening the angled wedge surfaces to clamp the bearing bracket in position.

TECHNICAL FIELD 
This invention relates to a connecting rod having an upper connecting rod 
eye, a connecting rod shank and a split lower connecting rod eye for 
receiving a crank pin, the connecting rod bearing cap of the lower 
connecting rod eye being in the form of a bearing bracket which is 
provided on the side remote from the connecting rod eye with a tapered 
surface which engages a complementary tapered counter surface, said 
counter surface being adapted for movement relative to the tapered surface 
of the bearing bracket by an adjusting means. 
BACKGROUND 
A connecting rod of this type, which is made of a composite fiber material, 
has been disclosed in the German Offenlegungsschrift DE-OS 34 16 011. In 
this connecting rod, the two connecting rod eyes are surrounded by a 
flexible clamping strap which encloses the connecting rod eyes from the 
outside. The strap is tensioned to exert a predetermined biasing force so 
that, when the connecting rod is in operation, the clamping strap is 
always subjected to a load in the tensile range and the connecting rod 
shank in the compression range. The clamping strap is associated with a 
mechanical tensioning device including a clamping bolt which extends 
transversely to the axial centerline of the connecting rod and which has 
attached to each of its ends a respective end of the clamping strap. The 
clamping bolt is provided with threaded portions which enable the clamping 
bolt to be adjusted along with a wedge and a wedge counter surface. The 
clamping strap, while in the relaxed condition, is placed over the 
connecting rod eyes and the connecting rod shank and is then adjusted to a 
predetermined load so that during operation the tensile loads will not 
cause the clamping strap to be appreciably stretched and the form-locking 
connection and load bearing engagement between the tensioning strap and 
the connecting rod shank will be fully maintained. 
The disadvantage of this prior-art connecting rod is that the clamping 
arrangement for the bearing bracket consists of three parts, namely two 
nuts and a clamping bolt. Furthermore, the clamping bolt is relatively 
complex in design since it is a non-circular part with threaded ends which 
cannot be made on a lathe, nor can it be simply cast or be made on a 
milling machine. But more importantly, in the case of a connecting rod 
made of metal, especially one that is cast, the clamping bolt cannot be 
mounted into a bearing yoke for the bearing bracket. In the case of the 
prior-art connecting rod, this is possible only because the clamping 
straps are flexible and therefore enable the clamping bolt with the 
threaded ends to be placed therebetween. Another shortcoming in this 
arrangement is that the assembly operation is costly and time consuming 
because the two threaded ends must be accessible to enable adjustment of 
the clamping bolt. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a connecting rod of the 
type described in the foregoing which enables, even in the case of a rigid 
connecting rod made of metal, such a a cast connecting rod, the loading of 
the bearing bracket to be accomplished with a minimum number of 
components, and wherein the manufacture of the clamping means can be 
simplified. 
This object is accomplished by forming the region of the lower connecting 
rod eye as a bearing yoke which has a bearing bracket mounted between two 
legs thereof. The bearing bracket is supported by a bolt which extends 
through bores in the yoke legs adjacent to their free ends and through a 
bore in a wedge that is adjustably carried between the legs. The wedge is 
provided with an angled counter surface that engages a mating angled wedge 
surface of the bearing bracket for adjustably clamping the bearing bracket 
in the yoke. A threaded portion of the bolt engages a corresponding 
threaded portion of the wedge bore to provide for adjustment of the wedge. 
The clamping means according to the invention is comprised of only two 
parts, namely the wedge and the bolt. The latter is in the form of a 
stepped diameter headed support pin provided with a threaded portion near 
the head end for adjusting the lateral position of the wedge but, for 
simplicity, this threaded pin is herein referred to as a bolt. The bolt 
can be manufactured on a lathe, and the wedge may be made as a cast part 
or machined from a slug as on a milling machine. 
When assembling the connecting rod on a crankpin, the bearing bracket is 
inserted between the legs of the bearing yoke and the wedge is positioned 
with its angled counter surface in engagement with the corresponding 
angled wedge surface of the bearing bracket. The bolt is then inserted 
through the bores of the legs and the wedge so that its threaded portion 
engages the corresponding threaded portion of the wedge bore. 
As long as the wedge is positioned at its farthest distance from the head 
of the bolt, the bolt will retain the wedge in position without loading 
the bearing bracket by causing a clamping force to be exerted between the 
wedge and the bearing bracket. As the bolt is threaded further into the 
wedge, the wedge will be caused to move towards the head of the bolt, and 
a clamping force will be generated between the wedge and the bearing 
bracket which will cause the bearing bracket to be tightened or loaded. 
This operation is accomplished by merely turning the head of the bolt with 
a suitable tool and, thus, eliminates the need for any additional 
manipulations at the end of the bearing yoke. 
Preferably, as shown, the wedge has its threaded portion located at the 
smaller end, facing the head of the bolt. As a result, the unthreaded 
length of the wedge bore, which acts as a bearing for the wedge on the 
unthreaded portion of the bolt, is relatively large. Furthermore, it is 
advantageous that the bores of the legs of the bearing yoke through which 
the bolt extends and the bore of the wedge in the region of the enlarged 
threaded end thereof be closely fitted to the diameter of the bolt. 
Other features of the invention will be apparent from the description of 
the single figure. It should be appreciated that all the individual 
features and combinations thereof must be considered to include any 
modifications that fall within the concept of the invention.

DETAILED DESCRIPTION 
In the illustrated embodiment, the connecting rod is comprised, 
essentially, of an upper connecting rod eye 1 for receiving a piston pin 
(not illustrated in the drawing), a connecting rod shank 2 and a split 
lower connecting rod eye 3 for receiving a crankpin (also not illustrated 
in the drawing). In the region of the lower connecting rod eye, the 
connecting rod is in the form of a bearing yoke 4 having second and first 
legs 5, 6, respectively, and a bearing bracket 7 clamped between the legs 
to enclose the crankpin. The bracket 7 closes the open end of the yoke 
which faces away from the connecting rod shank 2. The bearing bracket 7 is 
provided on its side facing away from the connecting rod shank 2 with a 
tapered or angled wedge surface 8 which is in engagement with a wedge 9 
having a correspondingly tapered or angled counter surface 10. The free 
ends of the legs 5 and 6 are provided with concentric bores 12 and 13 
which extend transversely to the axial center line 11 of the connecting 
rod, and the wedge 9 is provided with a concentric bore 14 and a threaded 
portion 15 formed in one end of the bore. The bores 12, 13 and 14 are 
adapted to receive a bolt 16 with a hexagon head having an innermost 
surface that, when installed, engages the outer surface of the leg 6 of 
the bearing yoke 4. The bolt includes a first guide portion 18 adjacent to 
the head 17 and of a diameter slightly smaller than the inner diameter of 
the bore 13 in which it is received. A second guide portion 19 is formed 
by the portion of the bolt extending from the end opposite the head and 
has a diameter slightly smaller than the bores 12 and 14 through which it 
extends. Between the two guide portions 18 and 19, the bolt 16 has a 
threaded portion 20 which is mateable with the threaded portion 15 of 
wedge 9. 
After insertion of the bearing bracket 7, with its angled surface 8 rising 
(i.e. angled away from the crankpin opening) in the direction of the first 
leg 6, wedge 9 is inserted with its angled counter surface 10 facing the 
angled surface 8 of the bearing bracket and with a thicker end of the 
wedge 9 in or near engagement with the second leg 5 of the bearing yoke 4. 
Thereafter, bolt 16 is inserted through bores 12 and 13 of the bearing 
yoke and through bore 14 of wedge 9, and its threaded portion 20 is 
threaded into the threaded portion 15 of wedge 9 until the inner surface 
of the bolt head 17 engages the outer surface of the first leg 6 of the 
bearing yoke 4. Upon further rotation of bolt 16, the threaded portion 20 
causes wedge 9 to move toward leg 6 of the bearing yoke 4 which causes the 
bearing bracket 7 to be urged or loaded against the yoke in the direction 
of the crankpin opening along the line of the axial center line 11 of the 
connecting rod 2.