Vehicle Speed Reducer Damping Coupler Rattle Reduction
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Solution Overview
Problem
Conventional speed reducers for vehicles suffer from poor rattle performance due to the inability of the elastic body to effectively absorb the reaction or impact between the worm shaft and the motor shaft, leading to deteriorated rotational rigidity and clearance compensation.
Innovation Solution
A speed reducer design featuring a damping coupler with an outer support portion for rotational force transmission and an inner support portion that can deform circumferentially to absorb reactions, eliminating the need for a separate elastic body by forming the coupler from an elastic material, thus reducing components and assembly complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant thickness elastic body is provided between the outer rotor and inner rotor, then the structure is simple, but the rotational rigidity is constant and the reaction or impact between the worm shaft and motor shaft cannot be effectively absorbed, deteriorating rattle performance
Solution Approach 1:
The damping coupler is designed with different thickness regions: a first thickness in the radial direction at the outer circumferential surface for rotational force transmission, and a second thickness greater than the first at the inner circumferential surface for absorbing reaction forces and impacts. This local differentiation allows the same component to perform multiple functions with different mechanical properties in different regions.
Solution Approach 2:
The damping coupler is divided into functionally distinct regions: an outer support portion for rigid rotational force transmission and an inner support portion with greater thickness for elastic deformation and impact absorption. The protrusions and recesses further segment the coupling interface to enhance both functions.
2Reliability
If a separate elastic body is used between the outer rotor and inner rotor, then the damping function is provided, but the number of components increases and assembly steps are complicated
Solution Approach 1:
The damping function previously provided by a separate elastic body is merged into the damping coupler itself. The coupler is formed from elastic material with varying thickness that provides both the structural coupling function and the damping function, eliminating the need for a separate elastic body component.
Solution Approach 2:
The damping coupler serves multiple functions: it transmits rotational force through the outer support portion, absorbs reaction forces and impacts through the inner support portion, and provides damping without requiring a separate component. This multi-functionality reduces the overall component count and simplifies assembly.
3Reliability
If the inner support portion is made with greater thickness, then the ability to absorb reaction or impact is improved, but the rotational rigidity may be reduced
Solution Approach 1:
The coupler has different thicknesses in different regions: the outer circumferential surface maintains a first thickness for rotational rigidity, while the inner circumferential surface has a second thickness for impact absorption. This local differentiation resolves the contradiction by providing the required property in each specific location.
Solution Approach 2:
The coupler is segmented into an outer support portion for rigid force transmission and an inner support portion for elastic deformation. The protrusions and recesses create discrete coupling points that maintain overall rigidity while allowing localized compliance for impact absorption.
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 rattle performance and response by effectively transmitting rotational forces while absorbing impacts, simplifying assembly and reducing component count.
Implementation Method 1
a damping slit is formed on the inner support portion, so that the inner support portion can be deformed in the circumferential direction to effectively absorb the reaction or impact of the worm shaft
Implementation Method 2
The outer support portion can perfectly transmit the rotational force between the worm shaft and the motor shaft
Data Source
AI summary
The present invention relates to a speed reducer for a vehicle. The speed reducer includes: a first coupler having, on one side thereof, a first coupling portion, to which a motor shaft or a worm shaft is coupled, and, on the other side thereof, a plurality of first protrusions, which are spaced apart from each other in a circumferential direction while protruding in an axial direction, in which the first protrusions are formed in a manner in which a circumferential width of each of the first protrusions is narrowed toward an inner side from an outer side so as to form a first outer support portion as a radial outer end and a first inner support portion as a radial inner end; and a second coupler configured to be coupled to the first coupler to transmit a rotational force to the first coupler.