Positive Engagement Clutch Nonlinear Spring Force Profile
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Solution Overview
Problem
The existing positive engagement clutch in all-wheel drive vehicles faces inefficiencies due to a linear spring force characteristic, which results in high electromagnetic actuation forces and reduced dynamics, as well as the need for a strong return force to ensure reliable meshing and disengagement of teeth under varying torque conditions.
Innovation Solution
A positive engagement clutch with a return element featuring a nonlinear force-deflection characteristic, utilizing a Belleville spring with a local force maximum at the meshing position, reduces spring force in the open position and increases the axial force during transition to the closed position, allowing for reduced electromagnet excitation and enhanced efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a linear spring force characteristic is used, then the clutch can be actuated, but the electromagnetic actuator requires high force and the dynamics are reduced
Solution Approach 1:
The patent applies a nonlinear spring force characteristic with a local maximum at the meshing position, changing the force parameter distribution along the actuation path. This allows the spring to provide high force precisely when needed for tooth meshing while requiring minimal force in the open position, thereby improving clutch dynamics without compromising engagement reliability.
2Reliability
If a strong return force is applied to ensure reliable meshing, then the engagement is reliable, but the electromagnetic actuator requires higher excitation current
Solution Approach 1:
The patent implements local quality by concentrating the spring force at the specific location where it is most needed - the meshing position of the teeth. The nonlinear spring characteristic ensures high force is applied locally during engagement while the force is minimized in other positions, particularly when the clutch is open. This localized force application maintains meshing reliability without requiring high excitation current throughout the entire actuation cycle.
3Loss of energy
If the spring force is reduced in the open position, then the efficiency increases, but the force available for meshing may be insufficient
Solution Approach 1:
The patent transforms the spring force parameter from a constant or linear distribution to a nonlinear distribution with a local maximum at the meshing position. This parameter change ensures that minimal force is required in the open position (improving efficiency) while a strong force is available precisely when the teeth need to mesh (ensuring reliable engagement). The force profile is optimized to match the actual operational requirements at different positions in the actuation path.
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
This design enhances the clutch's efficiency by minimizing spring force in the open position and providing a strong axial force for fast meshing, reducing the excitation current and ensuring reliable engagement and disengagement under high relative speeds and torque conditions.
Implementation Method 1
an elastic return element which applies a restoring force to the connection element in direction of the closed position
Implementation Method 2
the return element has a force/deflection characteristic with a local force maximum, where this force maximum in the actuation path coincides at least approximately with the meshing position
Implementation Method 3
an actuation device which is in operative connection with the connection element and which is configured to displace the connection element from the closed position to the open position
Data Source
AI summary
An axially actuatable positive engagement clutch which includes an input shaft with an input toothing and an output shaft with an output toothing. An axially displaceable connection element can occupy a meshing position which is located in an actuation path (s) between the open position and the closed position and in which the driving toothing engages with the input toothing or the output toothing for the first time during the transition from the open position into the closed position. An actuation device is configured to displace the connection element from the closed position to the open position, and an elastic return element which applies a restoring force to the connection element in direction of the closed position. The return element has a force/deflection characteristic with a local force maximum (F1) which coincides in the actuation path (s) at least approximately with the meshing position of the connection element.