Pulley Decoupler Spring Plate Ramp-Up Prevention
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Solution Overview
Problem
Existing decouplers for internal combustion engine generator belt drives experience issues with residual frictional torque causing relative torsion of spring plates, leading to undesirable ramping and potential axial bursting due to reduced installation space and erratic acoustics when the hub overtakes the pulley.
Innovation Solution
The decoupler design incorporates an additional non-rotatable bearing point supporting the rotatable spring plate, enhancing frictional torque to prevent relative rotation and reduce the risk of spring ends running up ramps, utilizing a clamping roller freewheel with double frictional contact at two bearing points to synchronize speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the one-way clutch has low residual friction to allow smooth overtaking, then the hub can overtake the pulley more easily, but the spring ends may ride up the ramps causing axial bursting and noise
Solution Approach 1:
The invention applies preliminary counteracting friction through the non-rotatable bearing point support before the ramp-up effect can occur. The frictional torque generated at this bearing point acts in the direction of rotation of the non-rotating spring plate, creating a restraining moment that prevents the spring ends from climbing the ramps during overtaking operations.
Solution Approach 2:
The non-rotatable bearing point support acts as an intermediary element between the rotatable spring plate and the stationary structure. It provides a controlled frictional interface that mediates the interaction between the rotating and non-rotating components, preventing unwanted relative motion while allowing the one-way clutch to function properly.
2Object-affected harmful factors
If the one-way clutch has high residual friction to prevent spring plate relative rotation, then ramp-up is prevented, but the overtaking operation becomes difficult and noisy
Solution Approach 1:
The invention segments the frictional torque generation into two distinct locations: the one-way clutch interface and the non-rotatable bearing point support. This segmentation allows each component to contribute differently to the overall frictional resistance - the bearing point provides controlled friction to prevent ramp-up, while the one-way clutch maintains low residual friction for smooth overtaking.
Solution Approach 2:
The invention changes the frictional parameters at different locations in the system. At the non-rotatable bearing point, the friction coefficient and normal force are designed to generate sufficient frictional torque to prevent ramp-up. At the one-way clutch, the friction parameters are optimized to maintain low residual friction. This differential parameter adjustment resolves the contradiction between preventing ramp-up and enabling smooth overtaking.
3Stability of the object's composition
If frictional torque is increased at the bearing points to prevent relative rotation, then spring plate stability improves, but the rotatable spring plate may stick and cause operational issues
Solution Approach 1:
The invention applies local quality differentiation by providing frictional support only at the non-rotatable bearing point where stability is needed, while leaving the one-way clutch interface with low friction to maintain rotational freedom. The frictional torque is localized to where it is most beneficial for preventing ramp-up, without affecting the overall overtaking operation.
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 significantly reduces the risk of spring plate relative torsion and associated acoustics issues by ensuring the rotatable spring plate rotates without relative speed, even when the hub overtakes, particularly when the one-way clutch has lower residual friction, such as in a sprag freewheel scenario.
Implementation Method 1
the elasticity of the helical spring smoothing out the rotational irregularities
Implementation Method 2
The frictional torque generated at one of the bearing points during overtaking of the hub then acts on the rotatable spring plate in the direction of rotation of the non-rotating spring plate
Implementation Method 3
The frictional torque generated at one of the bearing points during overtaking of the hub then acts on the rotatable spring plate in the direction of rotation of the non-rotating spring plate
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a decoupler (1) for rotationally driving a generator of an auxiliary-unit belt drive of an internal combustion engine, comprising: a pulley (2), a hub (4), and two bearing points (5, 6), at which the pulley is rotatably supported on the hub, a series connection of a helical torsion spring (13) and a one-way clutch (12), which allows the hub to overtake the pulley, and a spring plate (19), which is rotationally fixed in relation to the pulley or the hub, for the one spring end and a spring plate (18), which can be rotated in relation to the pulley and the hub, for the other spring end. The spring ends, which lie against ramp steps (20) of the spring plates, radially expand the helical torsion spring as the driving torque is transmitted. The frictional torque, produced in one of the bearing points when the hub is overtaking, acts on the rotatable spring plate in the direction of rotation of the rotationally fixed spring plate. The other bearing point, according to the invention, has a part that is rotationally fixed in relation to the rotationally fixed spring plate, on which part the rotatable spring plate is supported, a further frictional torque thus being produced, which acts on the rotatable spring plate in the direction of rotation of the rotationally fixed spring plate.