Switchable Ratcheting Clutch for Five-Mode Torque Control
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Solution Overview
Problem
Existing ratcheting clutches lack the ability to seamlessly switch between multiple operational modes, particularly the five modes of free-free, one-way, and lock-lock configurations, which limits their adaptability and efficiency in automotive transmissions.
Innovation Solution
A switchable ratcheting clutch design incorporating inner and outer rings, a cam ring, pawls, and ratcheting springs that transition between modes by rotating the cam ring relative to the inner ring, allowing for five distinct operational modes: free-free, two one-way, and two lock-lock modes, through the engagement and disengagement of pawls with the outer ring's tooth profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple two-mode ratcheting clutches are combined to achieve four-mode switching, then mode versatility is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple ratcheting mechanisms and pawls into a single integrated clutch structure, allowing five-mode switching (free-free, two one-way, and two lock-lock modes) without requiring multiple separate two-mode clutches. This merging approach achieves mode versatility while reducing overall device complexity compared to combining separate clutch units.
Solution Approach 2:
The clutch mechanism is designed with universal components that can perform multiple functions across different operating modes. The single clutch structure accommodates five distinct modes through the coordinated action of multiple pawls and ratchets, making each component multi-functional rather than requiring dedicated components for each mode.
2Adaptability or versatility
If pawls are designed to engage tooth profile for bidirectional locking, then adaptability across modes is improved, but manufacturing precision requirements increase
Solution Approach 1:
Different pawls are designed with specialized local geometries optimized for their specific engagement requirements. Each pawl has uniquely shaped engagement surfaces that match corresponding tooth profiles, allowing precise bidirectional locking in specific modes without requiring all components to meet the highest precision standards simultaneously. This localized optimization reduces overall manufacturing precision requirements while maintaining adaptability.
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 precise control over rotational direction and prevention of rotation in specific modes, enhancing the clutch's adaptability and reducing parasitic drag torque, thereby improving the efficiency and reliability of automotive transmissions.
Implementation Method 1
a plurality of ratcheting springs. Each of the plurality of ratcheting springs urges a respective pawl radially toward the cam ring and positions the respective pawl with respect to the outer ring based on a relative rotational position of the cam ring with respect to the inner ring
Implementation Method 2
A plurality of return springs may act between the cam ring and the spring cage
Implementation Method 3
Ratcheting clutches, on the other hand, have pawls or other members that engage to stop relative motion in one direction and ratchet to permit relative motion in the opposite direction
Data Source
AI summary
A switchable ratcheting clutch achieves four different modes of operation based on a relative rotational position of a cam ring and an inner ring. In a central relative position, an outer ring can rotate freely in either direction with respect to the inner ring. In either extreme relative position, the outer ring is prevented from rotating in either direction relative to the inner ring. In intermediate positions one either side of the central position, the outer ring is permitted to rotate in one direction but not the other. A number of pawls are supported on the inner ring and pushed radially out of engagement with the outer ring by a spring on a spring cage. The spring cage moves with the cam ring between the one-way positions but the cam ring rotates relative to the spring cage when moving into the extreme positions.