Three-State Clutch Assembly for Low-Drag Directional Locking
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Solution Overview
Problem
One-way clutch designs experience drag losses and noise, vibration, and harshness (NVH) issues due to ratcheting of rockers and ramps during rotation in one direction, which are not effectively mitigated in existing designs.
Innovation Solution
A clutch assembly featuring a dog clutch ring with axially displaced positions for open, transition, and locked conditions, including a ratcheting assembly with rockers, ramps, and biasing springs, which allows for reduced drag and NVH by selectively engaging and disengaging components to manage rotational directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-way clutch design with ratcheting assembly is used, then rotational locking in one direction is achieved, but drag losses and NVH increase due to ratcheting of rockers and ramps
Solution Approach 1:
The clutch assembly transitions from a static ratcheting design to a dynamic three-state system. The dog clutch ring can be axially displaced to three positions: engaged state (rockers engage ramps for one-way locking), disengaged state (rockers disengage from ramps to eliminate drag), and locked state (dog clutch splines engage cam splines for bidirectional locking). This dynamic reconfiguration allows the system to adapt its locking mechanism based on operational requirements, eliminating continuous ratcheting drag while maintaining reliability.
Solution Approach 2:
The clutch assembly segments the locking function into two distinct mechanisms: the ratcheting assembly for one-directional rotational control and the dog clutch assembly for bidirectional rotational locking. By separating these functions and providing independent engagement paths, the system can selectively activate only the necessary locking mechanism, avoiding the continuous energy loss associated with traditional one-way ratcheting designs.
2Reliability
If a one-way clutch design with ratcheting assembly is used, then rotational locking in one direction is achieved, but noise, vibration and harshness (NVH) increase due to ratcheting
Solution Approach 1:
The system dynamically switches between locking mechanisms to minimize NVH. In the disengaged state, rockers are completely separated from ramps, eliminating ratcheting noise and vibration. The biasing springs maintain rockers in a retracted position during normal operation, preventing unwanted contact and associated NVH issues while preserving the ability to engage locking when needed.
Solution Approach 2:
The harmful ratcheting action is extracted and isolated to specific operational states. By providing a disengaged state where rockers are completely removed from interaction with ramps, the system eliminates the source of NVH problems during normal operation, while retaining the capability to engage the ratcheting mechanism only when rotational locking is actually required.
3Adaptability or versatility
If three axial positions are implemented for the dog clutch ring, then multiple operating conditions are achieved, but device complexity increases
Solution Approach 1:
The dog clutch ring serves multiple functions through its three axial positions: it controls the engagement of the ratcheting assembly, provides bidirectional locking capability, and enables a neutral disengaged state. This multi-functionality is achieved by integrating the dog clutch splines and cam splines interaction into the existing ratcheting assembly structure, allowing a single component to manage multiple operating modes without proportionally increasing overall system complexity.
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 solution reduces drag losses and NVH by allowing disengagement of rockers from ramps in the open condition, engaging them in the transition condition for directional control, and locking both components in the locked condition, thereby enhancing torque transmission and rotational stability.
Implementation Method 1
The biasing springs are configured to bias or drive the rockers away from the ramps when the dog clutch ring is in the first axial position
Implementation Method 2
the protrusions on the dog clutch ring drive the arms into the first set of pockets such that the plurality of rockers become engaged with the plurality of ramps
Implementation Method 3
the dog clutch splines engage with the cam splines and provide a fully locked mode or condition. In this mode, torque is transmitted via engagement between the dog clutch splines and the cam splines
Data Source
AI summary
A clutch assembly is disclosed herein that generally has at least three operating conditions: an open condition, a transition condition, and a locked condition. The operating conditions are achieved based on displacement of a dog clutch ring relative to a pocket ring and a cam ring. In the open condition, rockers of a ratcheting assembly are completely disengaged from ramps on a cam ring. In the transition condition, the rockers engage with the ramps on the cam ring to allow a ratcheting motion in one rotational direction and a locked state in the other rotational direction. In the locked condition, splines on the dog clutch ring engage with splines on the cam ring to provide a rotationally fixed connection in both rotational directions.