Epicycloid-Hypocycloid Speed Reducer Design
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Solution Overview
Problem
Conventional speed reducers, such as RV and harmonic drive reducers, face issues with high volume, weight, and cost, as well as limitations in reduction ratio and durability due to deformation and teeth difference friction.
Innovation Solution
A speed reducer design featuring an epicycloid-epicycloid or hypocycloid-hypocycloid mechanism with a rotating wheel having a convex and concave structure, where the convex structure is contacted with first rollers and the concave structure with second rollers, allowing for adjustable tooth numbers to achieve high reduction ratios and increased rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a RV reducer is used to achieve high reduction ratio and rigidity, then the reduction ratio and rigidity are improved, but the volume, weight, and cost increase
Solution Approach 1:
The speed reducer is divided into two independent stages: a first stage using a flexible element (harmonic drive mechanism) and a second stage using a rigid epicyclic gear mechanism. Each stage performs a portion of the total reduction, allowing the system to achieve high overall reduction ratios while keeping individual components smaller and lighter than a single-stage RV reducer would require.
Solution Approach 2:
The patent combines two different mechanical mechanisms with complementary characteristics: a flexible element (flex spline) that enables high reduction ratio with compact size, and a rigid epicyclic gear mechanism that provides structural strength and impact resistance. This composite approach creates a hybrid speed reducer that achieves both the compactness of harmonic drives and the durability of RV reducers.
2Volume of moving object
If a harmonic drive reducer is used to reduce volume and weight, then the size is reduced, but the rigidity and impact resistance decrease
Solution Approach 1:
The speed reducer is divided into two independent stages: a first stage using a flexible element (harmonic drive mechanism) and a second stage using a rigid epicyclic gear mechanism. Each stage performs a portion of the total reduction, allowing the system to achieve high overall reduction ratios while keeping individual components smaller and lighter than a single-stage RV reducer would require.
Solution Approach 2:
The patent combines two different mechanical mechanisms with complementary characteristics: a flexible element (flex spline) that enables high reduction ratio with compact size, and a rigid epicyclic gear mechanism that provides structural strength and impact resistance. This composite approach creates a hybrid speed reducer that achieves both the compactness of harmonic drives and the durability of RV reducers.
3Volume of moving object
If a harmonic drive reducer is used to achieve compact size, then the volume is reduced, but the use life decreases due to flex spline deformation
Solution Approach 1:
The speed reducer is divided into two independent stages: a first stage using a flexible element (harmonic drive mechanism) and a second stage using a rigid epicyclic gear mechanism. Each stage performs a portion of the total reduction, allowing the system to achieve high overall reduction ratios while keeping individual components smaller and lighter than a single-stage RV reducer would require.
Solution Approach 2:
The patent incorporates a rigid epicyclic gear mechanism as the second stage to provide structural support and prevent excessive deformation of the flexible element. The rigid gears act as a protective mechanism that limits the stress and deformation experienced by the flex spline during operation, thereby extending its service life and preventing premature failure.
4Reliability
If a two-stage RV reducer is used to increase reduction ratio capability, then the reduction ratio is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the harmonic drive mechanism and epicyclic gear mechanism into a single integrated speed reducer unit with shared components. The input shaft, output shaft, and housing structure are common to both stages, reducing the total number of components compared to two separate reducers connected in series. This integration simplifies the overall device structure while maintaining high reduction ratio capability.
Solution Approach 2:
The patent designs the speed reducer so that certain components serve multiple functions across both stages. For example, the input shaft transmits power to both the flexible element and the sun gear, and the output shaft receives power from both the circular spline and the planet carrier. This multi-functionality reduces the number of dedicated components and simplifies the overall structure.
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 design achieves a high reduction ratio while reducing volume and weight, enhancing durability and cost-effectiveness by minimizing component count and addressing issues of deformation and friction, thereby combining the benefits of RV and harmonic drive reducers.
Implementation Method 1
The eccentric wheel is eccentrically fixed on the second end of the first transmission shaft
Implementation Method 2
The convex structure is protruded from an outer periphery of the main body and has at least one outer tooth. The concave structure is concavely formed in a surface of the main body and includes at least one inner tooth
Implementation Method 3
The first roller assembly includes a first wheel disc and plural first rollers. The second roller assembly includes a second wheel disc and plural second rollers
Data Source
AI summary
A speed reducer includes a first transmission shaft, an eccentric wheel, a first roller assembly, a rotating wheel, a second roller assembly and a second transmission shaft. The rotating wheel includes a main body and an axle hole. The main body includes a convex structure and a concave structure. The convex structure is protruded from an outer periphery of the main body and has outer teeth. The outer teeth are contacted with the corresponding first rollers. The concave structure is concavely formed in a surface of the main body and includes inner teeth. The inner teeth are contacted with plural second rollers of the second roller assembly. The speed reducer of the present invention is an epicycloid-epicycloid speed reducer or a hypocycloid-hypocycloid speed reducer. Since the speed reducer is designed to have four operating situations, the speed reducer can have various reduction ratios.