Directional Slip Coupling With Reverse Torque Boost
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Solution Overview
Problem
Existing slip clutches in work machines, such as combine harvesters, face challenges in providing adjustable clamping force during reverse operation to unblock drivelines, which is either complex and expensive with hydraulic systems or inflexible with mechanical systems.
Innovation Solution
A slip coupling with a main friction-based and spring-operated slip clutch combined with an auxiliary jaw clutch that increases clamping force in the reverse direction by axial movement of one clutch part, actuated by mechanical springs, allowing higher torque transmission without hydraulic systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydraulic system is used to provide adjustable clamping force for unblocking the driveline in reverse direction, then the clamping force can be adjusted to higher levels, but the device complexity and cost increase significantly
Solution Approach 1:
The clutch assembly is segmented into multiple friction plates (first set and second set) that can be independently clamped by separate spring mechanisms. This allows different clamping forces to be applied to different plate sets, enabling direction-dependent torque characteristics without requiring a complex hydraulic system. The segmentation of the friction plate assembly into stacked groups enables independent force application from opposite directions.
Solution Approach 2:
The clutch system dynamically adjusts its clamping force based on the direction of rotation. During forward rotation, the first spring maintains a first clamping force on the first set of friction plates. During reverse rotation, the second spring applies a second clamping force on the second set of friction plates, which can be higher to enable unblocking. This dynamic adaptation allows the system to provide appropriate force for each operational phase without complex control systems.
2Device complexity
If a mechanical slip clutch with pre-tensioned springs is used, then the device complexity is reduced and cost decreases, but the clamping force becomes fixed and cannot be adjusted for reverse direction unblocking
Solution Approach 1:
The friction plate assembly is segmented into multiple independent groups (first set and second set of friction plates) that can be clamped by different spring mechanisms. This segmentation enables each group to respond independently to rotational direction, providing adaptability while maintaining mechanical simplicity. The stacked arrangement of friction plates allows multiple clamping zones to operate simultaneously or independently.
Solution Approach 2:
The clutch mechanism dynamically responds to the direction of rotation through the geometric arrangement of the friction plates and springs. When rotation direction changes, the engagement geometry automatically shifts which spring applies force to which friction plate group. This passive dynamic response provides adaptability without requiring active control systems, maintaining mechanical simplicity while achieving direction-dependent clamping force adjustment.
3Reliability
If a single clamping force is applied to the friction plates, then the slip clutch provides sufficient protection during overload, but the inertia in the system can block the driveline at higher torque during blockage conditions
Solution Approach 1:
The protection system is segmented into two independent clutch mechanisms operating in parallel: a first slip clutch for normal overload protection and a second slip clutch for blockage unblocking. Each clutch has its own friction plates and spring mechanism, allowing them to be optimized for different functions. The first clutch engages during forward rotation for standard protection, while the second clutch engages during reverse rotation to provide the additional force needed to overcome blockage inertia.
Solution Approach 2:
The clutch system dynamically switches between different protection modes based on rotational direction and load conditions. During forward rotation, the first spring-clutch combination provides protection at a lower torque threshold. During reverse rotation (unblocking phase), the second spring-clutch combination activates to provide higher clamping force, enabling the system to overcome blockage conditions. This dynamic switching allows the system to adapt its protection characteristics to the operational phase.
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 higher clamping force on friction plates during reverse rotation, preventing driveline blockage without the complexity of hydraulic systems, ensuring effective torque transmission and unblocking without additional mechanical complexity.
Implementation Method 1
This component uses friction plates which are clamped together to create a safety torque setting. During overload the static friction between the plates is no longer sufficient to transfer the demanded torque, causing the plates to slip relative to each other.
Implementation Method 2
A mechanical slip clutch operates by axially locking up the plates with pre-tensioned mechanical springs.
Implementation Method 3
The axial movement is initiated when the torque exceeds a given limit, lower than or equal to the torque setting of the slip clutch, and actuates an increase in the pre-tension of the mechanical spring or springs of the slip clutch.
Data Source
AI summary
A slip coupling for a work machine includes a main clutch in the form of a friction-based and spring-operated slip clutch. The slip coupling further includes an auxiliary clutch configured to maintain a pre-set spring-induced clamping force on friction plates of the slip clutch, when the slip coupling rotates in a forward direction, and further configured to be able to increase the spring-induced clamping force, when the slip coupling rotates in a reverse rotational direction. The increase of the clamping force is enabled by the fact that one of two auxiliary clutch parts is axially movable when the slip coupling rotates in the reverse rotational direction, the axial movement actuating an increase in pre-tension of mechanical spring or springs of the slip clutch. A work machine such as a combine harvester equipped with the slip coupling is also described.