Selectable Clutch Buffer Structure for Low-Backlash Torque Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing two-way clutches suffer from issues such as backlash, noise, poor responsiveness, and limited torque capacity due to rigid engagement and friction-based power transmission, and require significant force to switch operation modes, especially when large torques are involved.
Innovation Solution
A selectable clutch with a cam-type and ratchet-type one-way clutch mechanism that allows switching between operation modes using a wedging effect and frictional force, incorporating a buffer element and spring element to enable backlash-free rotation and reduce engagement force, even at high torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratchet clutch or dog clutch is used for rigid engagement, then torque transmission is reliable, but backlash occurs and noise increases
Solution Approach 1:
The patent employs dynamic engagement elements (sprags and rollers) that can tilt and rotate to accommodate rotational movements while maintaining torque transmission. The sprags and rollers are designed to tilt in response to rotation direction changes, enabling smooth transitions without rigid mechanical contact that causes backlash and noise.
Solution Approach 2:
The patent uses curved cam surfaces on the inner circumference of the outer ring that engage with the rollers and sprags. These curved surfaces allow for smooth, continuous engagement and disengagement, eliminating the abrupt tooth-like contact of traditional ratchet clutches that generates noise and backlash.
2Device complexity
If sprags tilt in the same direction as rotation to switch engagement, then the mechanism is simple, but time loss occurs and responsiveness deteriorates
Solution Approach 1:
The operating mechanism axially moves the cage holding the rollers and sprags to a preliminary engagement position before rotation occurs. This preliminary positioning ensures that the engagement elements are already in the correct orientation and position, eliminating time loss during rotation direction changes and improving responsiveness.
3Device complexity
If friction-based power transmission is used, then the structure is simple, but torque capacity becomes small relative to size
Solution Approach 1:
The patent divides the power transmission function into two separate one-way clutch mechanisms: one for clockwise torque transmission and another for counter-clockwise torque transmission. Each mechanism uses a dedicated engagement element (sprag or roller) that provides positive mechanical engagement rather than relying solely on friction, thereby increasing torque capacity while maintaining structural simplicity.
4Reliability
If cams or rollers engage at arbitrary position, then the clutch can lock in both directions, but switching to free mode or one-way lock mode requires large force when transmission torque is large
Solution Approach 1:
The patent introduces an operating mechanism that acts as an intermediary to axially move the cage holding the engagement elements. This intermediate mechanism provides the necessary force to disengage the cams and rollers from their locked positions, enabling easy switching between two-way lock mode, one-way lock mode, and free mode even when large transmission torques are present.
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
Enables high responsiveness, reduced backlash and noise, and secure torque capacity with simple structure, allowing mode switching with light force even under large torque conditions.
Implementation Method 1
a first clutch mechanism capable of transmitting rotation at an arbitrary rotational angle through a wedging effect of a locking member arranged in a biased manner by biasing means between a first rotation element and a second rotation element
Implementation Method 2
through a frictional force between the locking member and the first rotation element and the second rotation element
Implementation Method 3
a locking member arranged in a biased manner by biasing means
Data Source
AI summary
Provided is a selectable clutch with a simple structure, offers high responsiveness, operates with reduced backlash and noise, and allows switching with a light force even when a transmission torque is large. In each of rotation transmission paths provided with a first clutch mechanism capable of transmitting rotation between two rotation elements through the wedging effect and a frictional force of a locking member and a second clutch mechanism capable of transmitting rotation by engaging two engagement elements, a buffer element is provided which allows either or both of the engagement elements to move relative to the rotation element to which the engagement element is connected in the circumferential direction.