Three-Ball Pin Coupling for Steering Shaft Misalignment
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Solution Overview
Problem
Existing vehicle steering mechanisms face issues with misalignment of worm shafts due to wear, leading to vibration noise, torque transmission hysteresis, and backlash, particularly when increased motor torque is required for higher loads.
Innovation Solution
A three-ball stud coupling with a first connector and a second connector, featuring a three-shaft pin assembly, race assemblies, and a cage assembly, which includes resilient elements and floating balls to accommodate misalignment and absorb vibrations, ensuring stable torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor output torque is increased to adapt to vehicles with higher loads, then the driving capability is improved, but the surface wear of the plastic contact surface increases, leading to greater misalignment angle
Solution Approach 1:
The patent changes the material parameter of the contact surface from plastic to metal (steel ball and metal race assemblies), which has higher wear resistance. This allows the system to handle higher motor torques without excessive wear, thereby maintaining the misalignment angle within acceptable limits even under increased load conditions.
Solution Approach 2:
The patent introduces a coupling as an intermediary component between the motor and the worm gear. This coupling includes self-aligning bearings and flexible elements that can compensate for misalignment, acting as a mediator to protect the plastic contact surface from excessive stress and wear while transmitting the increased motor torque.
2Reliability
If the misalignment angle exceeds the coupling's compensation capability, then the torque transmission stability deteriorates, but increasing the coupling's self-alignment capability may reduce torsional rigidity
Solution Approach 1:
The patent segments the coupling into multiple functional components: self-aligning bearings for handling misalignment, flexible elements for compensation, and rigid elements for torque transmission. This segmentation allows each component to specialize in its function, maintaining torsional rigidity while achieving the necessary self-alignment capability.
Solution Approach 2:
The coupling employs a composite structure combining rigid materials (for torsional stiffness) and flexible materials (for self-alignment and compensation). This composite approach allows the coupling to simultaneously provide the structural integrity needed for torque transmission and the flexibility required to compensate for misalignment angles up to ±1.5°.
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 coupling effectively compensates for misalignment angles up to ±1.5°, reducing vibrations and preventing backlash, while maintaining torque transmission efficiency and stability under varying load conditions.
Implementation Method 1
the race assemblies are capable of providing a resilient force between the ball race and the cage assembly
Implementation Method 2
a cage assembly with floating balls to accommodate misalignment and absorb vibrations
Data Source
Figure 1~2
Figure 3~5
Figure 6~9
AI summary
A coupling with three ball studs, comprising a first connector (M) and a second connector (N) that are non-rotatably connected. The first connector (M) includes a stud assembly with three shafts (10), bearing ring assemblies (20), and a cage assembly (30). The three-shaft stud assembly (10) comprises a shaft (11) and three ball rings (13) that surround the shaft (11) and are spaced at intervals around the shaft (11). There are three bearing ring assemblies (20). Each ball ring (13) is connected to a bearing ring assembly (20). The cage assembly (30) defines the circumferential position of the bearing ring assemblies (20). The bearing ring assemblies (20) can provide an elastic force between the ball ring (13) and the cage assembly (30). When the ball ring (13) shifts circumferentially relative to the cage arrangement (30), the two sides of the bearing ring arrangements (20) remain in contact with the cage arrangement (30) in the circumferential direction.A steering mechanism is also provided.