Concentric Constant Velocity Joint for Low-Friction Misalignment
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Solution Overview
Problem
Existing constant velocity joints used in heavy-duty applications like marine propulsion and bulldozers are unreliable, prone to failure, and suffer from high inertial forces and friction losses, leading to potential damage and safety hazards.
Innovation Solution
A constant velocity joint design featuring concentric couplings with dynamically mirrored annular members and support structures that minimize inertial forces and friction, ensuring contained failure modes and precise angular velocity transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double cardan joint arrangement with self-centring mechanism is used to link off-set drive shafts, then constant velocity output is achieved, but the joint becomes very heavy with high inertia forces and considerable friction losses
Solution Approach 1:
The joint is divided into two separate concentric couplings (inner and outer) that operate independently but mirror each other's motion. Each coupling handles a portion of the velocity correction, allowing the system to achieve constant velocity output while distributing the mechanical loads and reducing overall weight compared to a single heavy double cardan joint.
Solution Approach 2:
The inner coupling is nested concentrically within the outer coupling, with both couplings sharing a common axis. This nested arrangement allows the two couplings to work together in a compact configuration, reducing the overall footprint and weight while maintaining the constant velocity function through their mirrored motion.
2Reliability
If a double cardan joint arrangement with self-centring mechanism is used, then constant velocity output is achieved, but the joint experiences high inertia forces and considerable friction losses
Solution Approach 1:
By segmenting the velocity correction function across two independent concentric couplings, each coupling operates with reduced angular deviations compared to a single double cardan joint. This segmentation reduces the friction losses in each individual coupling and overall energy dissipation while maintaining constant velocity output.
Solution Approach 2:
The two couplings are designed to dynamically mirror each other's motion, with their angular positions coordinated to cancel out velocity fluctuations. This dynamic coordination allows the system to maintain constant velocity output with smoother operation and reduced friction losses compared to static or less coordinated designs.
3Ease of operation
If a Thompson joint is used, then smoother operation is achieved, but the joint becomes unreliable with wear and centrifugal loadings causing it to break apart
Solution Approach 1:
The concentric coupling design incorporates inherent load distribution and stress mitigation features that cushion against centrifugal loadings and wear before they can cause failure. The mirrored motion of the two couplings balances dynamic loads, preventing the uncontrolled failure modes seen in Thompson joints while maintaining smooth operation.
Solution Approach 2:
The invention changes the geometric and operational parameters of the coupling system by using two concentric couplings with mirrored motion rather than a single Thompson joint configuration. This parameter change enables the system to achieve both smooth operation and improved reliability by distributing stresses and avoiding the failure modes of earlier designs.
4Power
If earlier constant velocity joints are used, then power transmission is achieved, but failure occurs in an uncontrolled manner leading to extensive damage and danger to life
Solution Approach 1:
The concentric coupling design with mirrored motion incorporates inherent safety features that cushion and contain potential failures. The dual-coupling architecture provides redundant load paths and stress distribution mechanisms that prevent uncontrolled failure modes, protecting against extensive damage and safety hazards while maintaining power transmission capability.
Solution Approach 2:
By changing the fundamental architecture from single-coupling designs to a dual concentric coupling system with mirrored motion, the invention alters the failure characteristics of the joint. This parameter change ensures that even under extreme conditions, failures are contained and controlled rather than leading to uncontrolled damage and safety hazards.
Data Source
Figure 1
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AI summary
A constant velocity joint comprising two concentric couplings (1, 2), a first coupling (1) comprising an inner member (211), an intermediate annular member (221) and an outer annular member (231), the members being concentric. The inner member (231) of the second coupling (2) is common to the outer member (231) of the first coupling (1). The members of the couplings are constrained to rotate one with respect to another and the outer member of the second coupling is constrained to rotate angularly in respect of the common member in a way that is the mirror image of the rotation of the inner member with respect to the common member.