Gearbox Thrust Pad Fastening Structure for Thermal Expansion
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Solution Overview
Problem
The pre-tightening force of bolts securing thrust pads in gearboxes decreases due to thermal expansion, leading to loosening and eventual failure of the gearbox components.
Innovation Solution
A fastening apparatus with a connection structure that includes a flange pad and bushing body, allowing for a reserved gap to compensate for thermal expansion, ensuring the thrust pad is securely attached to the carrying member without direct contact, thereby maintaining a stable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the thrust pad is pre-tightened through the bolt at ambient temperature, then the connection stiffness is sufficient, but the pre-tightening force decreases by 20% to 30% due to thermal expansion during operation
Solution Approach 1:
The patent introduces a reserved gap between the thrust pad and the carrying member to accommodate thermal expansion. This gap allows the thrust pad to expand radially without generating excessive axial force that would loosen the bolt, thereby maintaining stable mounting despite temperature fluctuations. The gap size is carefully controlled to prevent both excessive looseness and plastic deformation.
Solution Approach 2:
The patent uses the reserved gap as an intermediary element between the thrust pad and the carrying member. This gap acts as a buffer that absorbs the thermal expansion effects, preventing direct transmission of expansion forces to the bolt connection, thus maintaining the pre-tightening force and mounting stability.
2Reliability
If the thrust pad is tightly clamped to prevent loosening, then the mounting stability is improved, but the thrust pad undergoes plastic deformation due to thermal expansion
Solution Approach 1:
The reserved gap is designed with specific dimensional parameters that allow the thrust pad to expand freely within the gap without causing plastic deformation. The gap size is calculated based on the thermal expansion characteristics of the thrust pad material, ensuring that the pad can expand radially without generating excessive clamping forces that would lead to deformation.
Solution Approach 2:
The reserved gap serves as a pre-designed cushioning space that anticipates and accommodates thermal expansion before it can cause harmful effects. By providing this expansion space in advance, the patent prevents the thrust pad from undergoing plastic deformation while maintaining stable mounting.
3Temperature
If the aperture of the communication hole is increased to accommodate thermal expansion, then the thrust pad can expand freely, but the connection stiffness decreases
Solution Approach 1:
The patent applies local quality by creating a reserved gap in the axial direction while maintaining a tight fit in the radial direction. The communication hole aperture is optimized to provide just enough clearance for thermal expansion in the axial direction, while the radial connection remains stiff through the bolt and connection structure. This localized differentiation allows simultaneous achievement of thermal expansion accommodation and connection stiffness.
Solution Approach 2:
The patent resolves the contradiction by shifting the expansion accommodation from the radial dimension (communication hole aperture) to the axial dimension (reserved gap). The communication hole maintains its original size for radial stiffness, while the reserved gap provides the necessary clearance for axial thermal expansion, thus maintaining connection stiffness while accommodating temperature changes.
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 prevents plastic deformation of the thrust pad and maintains a stable connection, ensuring the gearbox components remain firmly attached, thus preventing failure.
Implementation Method 1
Because the coefficient of thermal expansion of the material of the thrust pad is greater than the coefficient of thermal expansion of the material of the bolt, the thrust pad expands in the radial direction
Implementation Method 2
A fastening apparatus with a connection structure that includes a flange pad and bushing body, allowing for a reserved gap to compensate for thermal expansion, ensuring the thrust pad is securely attached to the carrying member without direct contact
Data Source
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AI summary
Provided are a fastening apparatus and a gearbox. The fastening apparatus is for connecting a thrust pad (100) to a carrying member (200). The thrust pad (100) is provided with a first recess (101) and a communication hole (102) communicating with the first recess (101). The carrying member (200) is provided with a threaded hole (201). The aperture of the communication hole (102) is greater than the aperture of the threaded hole (201). The fastening apparatus includes a bolt (1) and a connection structure. An end cap (11) of the bolt (1) is disposed in the first recess (101). A screw (12) of the bolt (1) passes through the connection structure and is threaded into the threaded hole (201). The connection structure is able to be clamped between the end cap (11) and the carrying member (200).