Underground Lid Gradient Design for Vibration Control
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Solution Overview
Problem
Lids for underground structures often experience excessive biting force against the receiving frame, making them difficult to open and leading to rattling, vibration, and noise due to the existing configurations.
Innovation Solution
The lid design incorporates a gentle gradient on the receiving frame and lid body surfaces with elastic deformation features such as cutout portions and protruding parts, allowing for controlled movement and reduced friction, preventing excessive biting force and enhancing ease of opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer diameter of the lid body is slightly smaller than the inner diameter of the receiving frame (flat receiving structure), then the lid body can be easily installed, but a gap is formed between the outer peripheral portion of the lid body and the inner peripheral portion of the receiving frame, causing rattling, vibration, and noise
Solution Approach 1:
The receiving frame incorporates a gradient structure that allows dynamic adjustment of the lid body position. The gradient surface enables the lid body to naturally settle into a stable position where it contacts both the gradient surface and the shelf portion, eliminating gaps and preventing rattling while maintaining ease of installation.
Solution Approach 2:
The receiving frame features different structural characteristics in different regions: a gradient surface in the upper portion for guiding and positioning the lid body, and a shelf portion in the lower portion for supporting the lid body. This local differentiation allows the structure to simultaneously achieve easy installation and eliminate harmful vibrations.
2Object-affected harmful factors
If the outer peripheral portion of the lid body and the inner peripheral portion of the receiving frame are formed to have a steep gradient (gradient receiving structure), then rattling, vibration, and noise are suppressed, but excessive biting force is generated, making it difficult to open the lid
Solution Approach 1:
The receiving frame employs a gradient structure with controlled, moderate angles rather than steep gradients. This localized gradient design provides sufficient biting force to suppress rattling and vibration while maintaining manageable opening effort, resolving the contradiction between noise suppression and ease of operation.
Solution Approach 2:
The gradient angles of the receiving frame are optimized to specific ranges that balance two opposing requirements: steep enough to provide biting force for suppressing vibrations, but gentle enough to allow easy opening. This parameter optimization resolves the technical contradiction.
3Reliability
If the outer diameter of the lid body is equal to the inner diameter of the receiving frame with steep gradient, then the lid body bites into the receiving frame effectively, but much effort is needed to open the lid with an opening/closing tool
Solution Approach 1:
The gradient angles are precisely controlled within optimal ranges to achieve sufficient biting force for reliable operation while preventing excessive friction that would make opening difficult. This parameter optimization resolves the contradiction between reliability and ease of operation.
Solution Approach 2:
The gradient structure provides just enough biting force to suppress rattling and ensure reliable operation, rather than maximum possible biting force. This partial action approach achieves the necessary reliability without creating excessive opening effort.
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 design effectively suppresses rattling, vibration, and noise while allowing for easy opening by managing the biting force and friction between the lid and receiving frame, ensuring stable operation and reduced operator effort.
Implementation Method 1
the outer peripheral portion of the lid body undergoes elastic deformation
Implementation Method 2
a friction force is generated between the lid second surface part and the receiving-frame second surface part
Implementation Method 3
the self-weight of the lid body and the load applied by a vehicle travelling on the lid body, etc., are supported by the receiving-frame first surface part
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An inner peripheral portion (31) of a receiving frame (30) includes: a receiving-frame first surface part (40) with a gentle gradient, and a receiving-frame second surface part (42) which is formed below the receiving-frame first surface part and with a steeper gradient than that of the receiving-frame first surface part by reducing a diameter toward a downward direction of the receiving frame, and an outer peripheral portion (11) of a lid body (10) includes: a lid first surface part (16) with a gentle gradient; and a lid second surface part (18) which is formed below the lid first surface part and vertically toward a downward direction of the lid body, or with a steeper gradient than that of the receiving-frame second surface part by reducing a diameter toward the downward direction of the lid body, in which in a closed-lid state of the lid body, the lid first surface part (16) is supported by the receiving frame first surface part (40), and the lid second surface part (18) and the receiving-frame second surface part (42) are pressed against each other by a pressing force caused by elastic deformation of at least either one of the outer peripheral portion (11) of the lid body (10) and the inner peripheral portion (31) of the receiving frame (30).