Elastic Protrusions for Engine-Transaxle Junction Contact
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Solution Overview
Problem
In power units where an internal combustion engine and a transmission are fastened together with bolts, gaps can form between the junction surfaces due to processing variations, mounting errors, and thermal expansion, leading to vibration and noise issues, particularly in the bolt span portions where the fastening force is less effective, potentially causing resonance.
Innovation Solution
A fastening structure that includes protrusion portions in the bolt span areas between insertion holes on the junction surfaces of the internal combustion engine and transmission, which elastically deform under fastening pressure to maintain contact and support the surfaces, thereby preventing vibration and noise. The position and number of protrusion portions are strategically set to avoid resonance frequencies and maximize contact, and can be formed during the milling process for smoothing the surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple bolts are used to fasten the engine and transmission together, then the fastening strength is improved, but gaps still form in the bolt span portions due to processing variations, mounting errors, and thermal expansion
Solution Approach 1:
The invention introduces protrusion portions at specific locations within the bolt span portions of the junction surface. These localized protrusions provide additional contact points exactly where gaps are most likely to form, creating non-uniform local quality that addresses the specific problem areas without requiring additional bolts throughout the entire junction surface.
Solution Approach 2:
The protrusion portions are pre-formed on the junction surface before fastening occurs. This preliminary structural feature ensures that when the bolts are tightened, the protrusions are already positioned to prevent gap formation, proactively addressing potential contact instability before it can occur during operation.
2Manufacturing precision
If the junction surfaces are made rigid to maintain contact, then manufacturing precision is improved, but the structure becomes more complex and costly
Solution Approach 1:
Rather than requiring the entire junction surface to be precisely rigid, the invention introduces localized protrusion portions that provide the necessary contact stability. This approach maintains manufacturing simplicity for the overall surface while adding minimal local features only where needed to prevent gap formation.
3Object-affected harmful factors
If protrusion portions are added to prevent gap formation, then vibration and noise are reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The protrusion portions are created using localized machining operations that modify only specific areas of the junction surface. This approach minimizes the impact on the overall manufacturing process while effectively addressing vibration and noise issues at the critical bolt span portions where gaps would otherwise form.
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
This solution effectively restrains vibration and noise by maintaining contact between the junction surfaces, preventing resonance, and can be implemented with minimal additional operational steps and cost, ensuring stable vibration characteristics even with surface deformations due to thermal expansion.
Implementation Method 1
the protrusion portion may elastically deform due to pressing force caused by fastening of the internal combustion engine and the transmission via the bolts in such an elastic deformation manner that the junction surface of the internal combustion engine and the junction surface of the transmission closely contact each other
Implementation Method 2
the protrusion portion, which has been elastically deformed, tends to restore its original shape while remaining in contact with the junction surface that the protrusion portion faces
Data Source
AI summary
A hybrid transaxle 200 that is a transmission is provided with a junction surface 20 that contacts a junction surface of an internal combustion engine. A bolt span portion 20a of the junction surface 20 is provided with a protrusion portion 25 that elastically deforms so that the internal combustion engine-side junction surface and the hybrid transaxle 200-side junction surface 20 closely contact each other.