Patent Application
20070131191
The present invention relates to internal combustion engines, and, more particularly, to a connecting rod for interconnecting a crankshaft with a piston.
An internal combustion (IC) engine typically includes a block with a plurality of pistons reciprocally disposed within a plurality of corresponding combustion cylinders. Each piston is connected via a connecting rod with a crankshaft which provides mechanical output power from the IC engine. For interconnecting with the crankshaft, the connecting rod includes a cap connected with a rod. The cap may be machined separate from and attached to the rod, or formed integral with and separated (e.g., fractured) from the rod.
Connecting rods are also used in other applications including a reciprocating piston connected with a crankshaft. For example, connecting rods are also used in compressor applications.
Currently there are two types of connecting rod joint designs between the cap and rod: those with a 90 degree orientation between the longitudinal axis of the rod and the separating plane of the cap, and those with a 45 degree orientation between the longitudinal axis of the rod and the separating plane of the cap. Both designs are used for a variety of reasons to do with design and assembly considerations. The use of a 45 degree joint is primarily for assembly when the cylinder bore is smaller than the connecting rod width. Connecting rod bearing halves are installed in the cap and rod such that the split line between bearing halves is the same as the split line between the cap and rod. With the highly loaded area of a connecting rod in the axis of the rod and on 45 degree designs, the bearing joint is near the area of high load. Engine bearings worked well prior to emission regulations when the peak loading occurred in a location near the axis of the connecting rod but away from the joint. However, recent emissions laws have resulted in delayed peak loading so that it now occurs much closer to the bearing joint. Engine testing has demonstrated that loading can occur even beyond the joint line resulting in poor bearing performance. Contemplated solutions to this problem, such as reversing the installation of the connecting rod assembly in the machine, may require complete redesign of cylinder blocks and assembly tooling.
What is needed in the art is a connecting rod with reduced loading in the area of the split line between the cap and rod, while maintaining ease of manufacture and assembly.
The present invention provides a connecting rod with a joint between the cap and rod having offset split lines.
The invention comprises, in one form thereof, a connecting rod for interconnecting a crankshaft with a piston in an internal combustion engine. The connecting rod includes a cap connected to a rod and defining a crankshaft bore therebetween. The crankshaft bore includes an axis of rotation. The cap includes a first end defining a first split line and a second end defining a second split line. The first split line and the second split line are offset relative to a plane extending through the axis of rotation.
The invention comprises, in another form thereof, an internal combustion engine including a block with at least one combustion cylinder, at least one piston, a crankshaft, and at least one connecting rod. Each piston is reciprocally disposed within a corresponding combustion cylinder. Each connecting rod interconnects the crankshaft with a corresponding piston. Each connecting rod includes a cap with a first end and a second end. The first end defines a first split line and the second end defines a second split line. The first split line and the second split line are substantially parallel and non-coplanar relative to each other.
Referring now to the drawings, and more particularly to
Referring now to
Cap 26 includes a first end 38 defining a first split line 40, and a second end 42 defining a second split line 44. First split line 40 and second split line 44 are substantially parallel and non-coplanar relative to each other. More particularly, first split line 40 and second split line 44 are offset from either side of plane 32 a distance X1 and X2, respectively. In the embodiment shown, first split line 40 and second split line 44 are offset a substantially same distance (e.g., 10 mm) from plane 32. It is also possible that first split line 40 and second split line 44 can be offset different distances from plane 32. Moreover, it is also contemplated that first split line 40 and second split line 44 can be slightly non-parallel to each other.
First end 38 includes a first fastener bore 46 and second end 42 includes a second fastener bore 48, each of which receives a cap screw 50 which threadingly engages a female threaded opening (not numbered) in the mating end of rod 24. First fastener bore 46 and second fastener bore 48 are substantially parallel to each other and substantially perpendicular to plane 32.
Referring now to
According to the present invention, connecting rods 12 and 60 position the split lines between the cap and rod away from the areas of high mechanical loading. This results in an improved oil film, decreased friction and reduced wear between the connecting rod and crankshaft.
Although the connecting rod of the present invention is shown and described above for use with an internal combustion engine, it is also to be understood that the connecting rod of the present invention may be used in other applications interconnecting a piston and crankshaft. For example, the connecting rod of the present invention may be used in compressor applications.
Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
