Connecting Rod Closing System with Wedge Locking
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Solution Overview
Problem
Conventional connecting rods face issues with load loss and non-uniform pre-loading at the body/cap interface, particularly under cyclic stresses, and are prone to failure when made from materials other than metal, due to the use of threaded fastening elements and asymmetrical wedge-like elements.
Innovation Solution
A connecting rod design featuring a beam-shaped fastening element and wedges that form a uniform, symmetric load path, eliminating the need for threaded elements and ensuring a stable interface, allowing for efficient stress distribution and reduced risk of failure, even when made from non-metallic materials like thermoplastics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If threaded fastening elements (bolts and nuts) are used to connect the connecting rod cap to the body, then the connecting rod can be assembled and disassembled easily, but load loss occurs at the body/cap interface under cyclic stresses and failure cracks can develop
Solution Approach 1:
The patent removes the threaded fastening elements (bolts and nuts) from the connecting rod structure entirely. Instead, it uses a permanent bonding system where the cap is bonded to the body using adhesive material in a recess, eliminating the source of stress concentration and load loss associated with threaded connections under cyclic loading
Solution Approach 2:
The patent incorporates a recess in the connecting rod body and applies adhesive material beforehand before assembling the cap. This preliminary preparation ensures uniform pre-loading distribution from the start, preventing the development of failure cracks that would occur with threaded fasteners under cyclic stresses
2Strength
If wedge-like elements are used to lock the fastening element, then the connection can be secured against the connecting rod cap, but the pre-loading distribution becomes non-uniform causing distortions and increasing the risk of breaking the oil film
Solution Approach 1:
The patent eliminates the asymmetrical wedge-like locking elements and replaces them with a symmetrical bonding system. The adhesive material is distributed uniformly in a recess that spans the width of the connecting rod body, creating symmetrical pre-loading distribution that prevents distortions and maintains oil film integrity
Solution Approach 2:
The patent uses homogeneous adhesive material distributed evenly throughout the recess in the connecting rod body. This homogeneous bonding approach ensures uniform pre-loading distribution across the entire cap-body interface, eliminating the non-uniform stress distribution caused by asymmetrical wedge elements
3Weight of moving object
If threaded fastening elements are used in connecting rods made from non-metallic materials, then the connecting rod can be constructed with lighter materials, but the threaded elements cause failure cracks and load loss
Solution Approach 1:
The patent removes threaded fastening elements from the design, enabling the use of non-metallic materials like thermoplastics or composites without the risk of stress concentration and failure cracks that would occur at threaded connection points in lighter materials
Solution Approach 2:
The patent explicitly enables the use of composite materials or non-metallic materials for the connecting rod by replacing mechanical threaded fasteners with a bonding system. The recess and adhesive approach is particularly suited for plastic or composite materials that would be weakened by threaded holes and fasteners
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces load losses and stress concentrations, enabling a more robust and uniform pre-loading distribution, which enhances the connecting rod's resistance to tensile stresses and allows for the use of lighter, non-metallic materials while maintaining mechanical performance.
Implementation Method 1
the two wedges, inserted in the seat between the fastening element and the connecting rod cap, form a force path from the connecting rod cap to the fastening element
Implementation Method 2
a prismatic guide, coupled with a track present on two sides of the connecting rod cap, constraining the connecting rod cap to translation
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3C
AI summary
The present invention relates to a connecting rod (1) provided with a closing system with a translation constraint, wherein the connecting rod (1) comprises a connecting rod body (100) comprising a hole (60) at one end (100a) and two arms (6,7) at the opposite end shaped such as to define therebetween a circular arc; the connecting rod further comprises a connecting rod cap (2) removably inserted between the two arms (6,7) and provided with an indentation (19a) shaped in such a way that, when the connecting rod cap is inserted between the two arms (6,7), the indentation forms a circular opening (40) with the circular arc formed by the arms of the connecting rod body; the connecting rod (1) further comprises a seat (21,31) obtained on the connecting rod cap (2) and on the arms (6,7) into which a fastening element (3) is housed and two wedges (4,5) inserted in said seat between the fastening element (3) and the connecting rod cap (2) to lock the connecting rod cap (2), in particular two surfaces (23,24) thereof against corresponding first shoulders (10,9) of the arms (6,7) of the connecting rod body (100); the fastening element (3) is a beam-shaped element whose section increases from the ends towards the center, each of the two wedges (4,5) is inserted in the seat through a corresponding arm of the connecting rod body and is arranged so as to have a contact surface (31a,31b) in contact with the connecting rod cap (2); the wedges (4,5) through the contact surface (31a,31b) form a force path from the connecting rod cap (2) to the fastening element (3), that in turn ends the path by discharging the force on the seat (31) of the element (3) formed in each one of the arms (6,7); therefore the contact surface (31a,31b) is arranged in a plane orthogonal to a straight line passing through the geometric center of the hole (60) and of the circular opening (40) and it is not in direct contact with the arms (6,7) that is with their surfaces (110,120), but between the contact surfaces of the wedge (31a,31b) and the surfaces (110,120) of the arms (6,7) respectively there is little clearance but the connecting rod (1) is closed and constrained to translation. The present invention relates also to any two-part support (500,500',500") of a rotating shaft (1000',1000") provided with a closing system with translation constraint, wherein the two-part support (500,500',500") comprises: a body (510,510',510"), a cap (520,520',520"), two wedges (530,530',530") and a fastening element (540,540',540"); the body (510,510',510") comprises two arms (511a,511b), each one comprising a prismatic guide (512), an opening (513) and a seat (514); the cap (520) comprises a hole (521) and a pair of tracks (522); when the cap (520,520',520") is coupled to the body (510,510',510") by the insertion of the prismatic guides (512) in the tracks (522), the two wedges (530,530',530") are inserted in the openings (513) and the fastening element (540,540',540") is inserted in the hole (521) and in the seats (514), the two-part support (500,500',500") is closed and constrained to translation.