Torque Tube Interference Fit Rigidity for Off-Highway Leakage
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Solution Overview
Problem
Interference fits in torque tubes of off-highway vehicle wheel drive assemblies can relax under cyclic torsional loading, leading to potential oil leakage due to stress profile changes, which results in vehicle downtime for maintenance and repair.
Innovation Solution
A torque tube design featuring a ring gear with internal teeth and a barrel portion joined at a radial location inward from the mating portion, enhancing the rigidity of the interference fit and incorporating a clamping groove and seal element to maintain the interference fit during torque transfer, thereby preventing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an interference fit is used to secure the torque tube to the oil seal, then the connection is essentially permanent and does not require fasteners, but the interference fit can relax under cyclic torsional loading leading to gaps and oil leakage
Solution Approach 1:
The torque tube is divided into two distinct segments: the ring gear portion and the barrel portion. These segments are joined through a controlled interference fit that can be precisely engineered to maintain contact pressure. The segmentation allows each portion to be optimized for its specific function while maintaining a reliable connection interface that resists relaxation under cyclic loading.
Solution Approach 2:
The interference fit parameters (interference amount, contact pressure, material properties) are carefully selected and controlled to ensure that the connection maintains sufficient friction force under cyclic torsional loading. By optimizing these parameters, the design achieves a balance between ease of assembly and long-term reliability without requiring fasteners.
2Strength
If the barrel portion is joined at the radial location inward from the mating portion, then the rigidity of the interference fit is enhanced, but the device complexity increases
Solution Approach 1:
Instead of increasing complexity in the axial dimension with additional fasteners or locking mechanisms, the design utilizes the radial dimension by positioning the barrel portion's joining location inward from the mating portion. This dimensional approach enhances the rigidity of the interference fit by creating a more favorable stress distribution and contact geometry, while avoiding additional components.
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 maintains the interference fit during torque transfer, reducing the likelihood of oil leakage and enhancing the durability of the torque tube, thus minimizing maintenance and repair needs.
Implementation Method 1
interference fits are often used for releasably securing parts in an essentially permanent fashion that, once established, is not dependent on fasteners. Interference fits, however, rely upon compressive stresses in the fitted interference surfaces
Implementation Method 2
the friction that holds the parts together is often greatly increased by compression of one part against the other
Data Source
AI summary
A torque tube includes a ring gear having a first axial end, a second axial end opposite the first axial end, an inner surface including a plurality of teeth, and an outer surface with a mating portion formed adjacent to the first axial end of the ring gear. The torque tube also includes a barrel portion joined to the second axial end of the ring gear at a radial location inward from a radial location of the mating portion. The barrel portion extends axially away from the ring gear.