Wedge Unidirectional Joint for Reverse Torque Locking
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Solution Overview
Problem
Existing unidirectional joints, such as those using steel balls, face challenges in altering contact surface pressure and efficiently inhibiting driving force transmission from the output side to the input side, particularly in applications like vehicle seats where precise control of rotational forces is required.
Innovation Solution
A unidirectional joint design incorporating a wedge member with a non-rolling element, an immovable ring, and followers that displace the wedge member between locked and unlocked positions, allowing for controlled pressure contact and preventing reverse force transmission, utilizing a transmission part with protrusions and a retainer to manage the wedge member's posture and engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steel ball is used as a unidirectional joint to interrupt driving force transmission, then the driving force transmission from output shaft to input shaft is interrupted, but the contact surface pressure cannot be altered depending on specifications
Solution Approach 1:
The patent changes the physical state and geometric parameters of the joint elements. By transitioning from spherical steel balls to wedge-shaped members with inclined surfaces, the contact mechanism changes from point contact to surface contact, enabling adjustable contact pressure through the wedge angle and displacement amount while maintaining the unidirectional locking function.
Solution Approach 2:
The patent introduces dynamic adjustability to the joint system. The wedge members can be displaced radially to adjust the contact pressure with the circumferential surface, allowing the system to adapt to different load conditions and specifications while maintaining reliable driving force interruption in the reverse direction.
2Reliability
If a steel ball comes in pressure contact with the clutch housing to stop rotation, then the worm shaft rotation is stopped, but the contact surface pressure cannot be altered depending on specifications
Solution Approach 1:
The patent changes the contact mechanism from spherical point contact to wedge-shaped surface contact. The wedge members engage with inclined surfaces of the circumferential surface, allowing the contact pressure to be adjusted by changing the radial displacement of the wedge members, thereby enabling specification-dependent pressure control while ensuring reliable worm shaft rotation stopping.
3Stress or pressure
If a wedge member with non-rolling element is used, then contact surface pressure can be controlled, but the device complexity increases with multiple followers and cams
Solution Approach 1:
The patent divides the wedge member control into separate functional components: first followers for displacement control, second followers for positioning, release cams for unlocking, and pressure cams for loading. This segmentation allows each component to be optimized for its specific function, managing the overall complexity through modular design while achieving precise contact pressure control.
Solution Approach 2:
The patent designs the wedge members to perform multiple functions: they act as locking elements to prevent reverse rotation, as pressure control elements through radial displacement, and as engagement elements with the circumferential surface. The followers and cams work together to provide both positioning and pressure control functions, reducing the need for separate dedicated 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
This design effectively transmits driving force from the input side to the output side while preventing reverse transmission, ensuring reliable operation and maintaining appropriate contact surface pressure, even under varying force conditions, enhancing the functionality of vehicle seat actuators.
Implementation Method 1
a wedge member (15) including a pressure contact portion (15A), which comes in pressure contact with a circumferential surface of the immovable ring (14)
Implementation Method 2
a first follower (15B) provided in the wedge member (15), the first follower (15B) displacing the wedge member (15) to the unlocked position by receiving a pressing force from the release cam (16A)
Data Source
AI summary
A unidirectional joint includes a wedge member having a pressure contact portion that comes in pressure contact with an inner circumferential surface of an immovable ring. The wedge member includes a first follower displacing the wedge member to an unlocked position by receiving a pressing force from a release cam when a driving force is input to an input side protrusion and a second follower displacing the wedge member to a locked position by receiving a pressing force from a pressure cam when a driving force is input to an output side rotating part.