Monostable Sliding Sleeve Coupling for Low-Drag Torque Transfer
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Solution Overview
Problem
Existing torque transmission systems in hybrid and electric vehicles suffer from inefficiencies due to drag torque in clutches, which are exacerbated in wet conditions, and require large, heavy clutches to handle high torque, resulting in a significant footprint and reduced energy efficiency.
Innovation Solution
A coupling system featuring a sliding sleeve with intermediate engagement interfaces and an actuator with an elastic return member, providing a 'normally open' coupling function and minimizing transient torque, which includes a rotating kinematic link and an annular pad to reduce drag torque and maintain compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If clutches are used to transmit high torque in torque transmission devices, then the torque transmission capability is improved, but the size and weight of the clutches increase significantly
Solution Approach 1:
The clutch assembly is divided into multiple friction disks (first friction disks and second friction disks) that can be selectively engaged. The coupling system segments the torque transmission path, allowing only necessary clutch elements to be activated based on operating conditions, thereby reducing the effective weight and size of the engaged clutch components while maintaining high torque capability when needed.
Solution Approach 2:
The system dynamically selects which clutch to engage (first or second clutch) based on operating conditions such as vehicle speed and torque requirements. This dynamic engagement strategy ensures that clutches are only actively transmitting torque when necessary, reducing the effective weight impact during operation while preserving full torque transmission capability when required.
2Force
If clutches are used to transmit high torque, then the torque transmission capability is improved, but the footprint of the clutch system increases
Solution Approach 1:
The coupling system employs a nested structure where the sliding sleeve is received within the clutch assembly, and friction disks are arranged in concentric configurations. This nesting allows multiple clutch elements to occupy overlapping spatial volumes, significantly reducing the overall footprint of the clutch system while maintaining the capability to transmit high torque through the engaged friction disks.
Solution Approach 2:
The system utilizes the axial dimension extensively, with friction disks arranged in series along the axis of rotation rather than spreading out radially. The sliding sleeve moves axially to engage or disengage clutches, and the nested arrangement of friction disks exploits the axial direction to pack multiple torque transmission elements into a compact radial footprint.
3Loss of energy
If a connection element is added to interrupt rotational drive and eliminate drag torque, then energy efficiency is improved, but the device complexity increases
Solution Approach 1:
The coupling system merges multiple functions into the sliding sleeve component: it acts as both the engagement element that connects/disconnects clutches and the actuator interface that responds to control signals. The elastic return member combines the functions of actuation and drag torque elimination. This merging reduces the number of separate components needed to achieve drag torque elimination, thereby limiting the increase in device complexity while successfully reducing energy losses.
Solution Approach 2:
The elastic return member provides self-service by automatically returning the sliding sleeve to the disengaged position when actuation force is removed, and by automatically eliminating drag torque on the first clutch when the second clutch is engaged. This self-service mechanism eliminates the need for additional active control systems to manage drag torque, improving energy efficiency without proportionally increasing device 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 enhances energy efficiency by limiting drag torque and reducing the size and weight of the clutch system, while maintaining high starting torque and maximum speed capabilities, thus optimizing vehicle performance and user comfort.
Implementation Method 1
an elastic return member fixed in rotation about the axis of revolution in the fixed frame of reference, the mobile member being capable, by means of the kinematic link, of driving the sliding sleeve from the retracted position to the coupling position and of loading the elastic return member by passing from the rest position to the activated position, the elastic return member being able, while unloading, to return, by means of the kinematic link, the mobile member from the activated position to the rest position
Data Source
AI summary
A coupling system for a torque transmission device of a motor vehicle includes a sliding sleeve. An actuator including a mobile member movable between a rest position and an activated position is linked to the sliding sleeve by a rotating kinematic link and by an elastic return member fixed in rotation about the axis of revolution. The mobile member is capable, by means of the kinematic link, of driving the sliding sleeve from the retracted position to the coupling position and of loading the elastic return member by passing from the rest position to the activated position. The elastic return member is able, while unloading, by means of the kinematic link, to return the mobile member from the activated position to the rest position and the sliding sleeve from the coupling position to the retracted position.