Selectable One-Way Clutch Torque Spike Management
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Solution Overview
Problem
Transmissions without a neutral mode or friction clutch are prone to damage from torque spikes, as they constantly transmit torque from the engine to the drive wheels, with no mechanism to prevent excessive torque transfer.
Innovation Solution
A method using a selectable one way clutch in a hybrid vehicle's transmission that disengages when the electric motor is providing propulsive torque and wheel torque is actively managed by a vehicle control system, allowing the shaft to rotate relative to the housing and preventing excessive torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the transmission is configured without a neutral mode, then the transmission structure is simplified, but torque spikes from drive wheels are communicated through the transmission causing potential damage to transmission components
Solution Approach 1:
The patent applies a selectable one-way clutch that can dynamically change its engagement state based on operating conditions. The clutch is engaged during normal operation to prevent reverse rotation, but can be disengaged when torque spikes are detected, allowing the shaft to rotate freely relative to the housing. This dynamic state change protects transmission components from torque spikes while maintaining the simplified structure of omitting a neutral mode.
Solution Approach 2:
The selectable one-way clutch acts as an intermediary element between the shaft and housing. It mediates the torque transmission by selectively allowing or blocking rotational movement based on clutch engagement state. When disengaged, it allows torque spikes to bypass the transmission components; when engaged, it maintains the torque connection for normal operation.
2Reliability
If a selectable one way clutch is added to protect against torque spikes, then transmission component protection is improved, but device complexity increases
Solution Approach 1:
The selectable one-way clutch is designed to operate automatically based on the direction of torque application. When torque spikes cause reverse rotation attempts, the clutch self-actuates to disengage or engage based on the rotational direction, without requiring complex external control systems. This self-service mechanism protects transmission components while minimizing added complexity.
Solution Approach 2:
The patent replaces complex mechanical protection systems (such as friction clutches or neutral modes) with a simpler selectable one-way clutch mechanism. The one-way clutch uses a more straightforward mechanical design that achieves the same protective function with fewer components and less complexity.
3Productivity
If the selectable one way clutch remains engaged during wheel torque management, then torque transmission efficiency is maintained, but excessive torque can damage transmission components
Solution Approach 1:
The control system monitors wheel torque conditions and provides feedback to the selectable one-way clutch control. When wheel torque management is active (such as during anti-lock braking or traction control), the system detects this condition and signals the clutch to disengage, preventing torque spikes from damaging transmission components while maintaining efficient torque transmission during normal operation.
Data Source
AI summary
A method of controlling a selectable one way clutch operable to selectively couple a shaft to a housing of a transmission includes determining if an electric motor is currently operating, and if the selectable one way clutch is currently engaged to couple the shaft to the housing. It is further determined whether or not wheel torque of at least one wheel is currently being actively managed by at least one vehicle control system. When the electric motor is operating with the selectable one way clutch engaged, and wheel torque of at least one wheel of the hybrid vehicle is currently being actively managed by at least one vehicle control system, then selectable one way clutch is disengaged to release the shaft from the housing and allow rotation of the shaft relative to the housing.